OCT 27 1892  PG-5 TOP and BOT of cource

OCT 27 1892 AMERIdA N" ' M ACITINISr2 
hook, because, ordinarily, these hooks would be set in the notches and, hooks B and C slung thereon. The variety of uses to which the turn-buckle, A, can be Alitit, will 'apparent to many who are now making shift to get along by methods which are simply ridiculous, by comparison, on account of their inadaptation to the wotk for which they have been planned, and that have cost, perhaps, more than tools adequate to the work to be done would have cost. A good sling chain may, in many in-stances, be made to do duty for the beam and slings, by the use of a stout oak timber, as seen at A, Fig. 11, the timber to be strengthened at the ends by an iron shoe which allows of link pins being driven in, as seen at B and C. This combination will recommend itself as a time saver fn scores of cases where the object to be reversed is not too heavy to make such a means impractica-ble. Fig. 12 is a change hook, and, as its name implies, is used where material must be pass-ed from one crane to the other without rest-ing the load; its use is so common as to make any description here superfluous; it would be well to observe, however, that inasmuch as men must necessarily be very near during the process of changing, the greatest care should be taken in selecting the stock for as well as the forging of this hook. Sometimes the eyes A and B are close-welded to the body of the hook with the view of augmenting the strength, but it is much handier for use when they are left open, as shown ; therefore, to combine utility with strength, let them be made more massive. Fig. 13 serves to illustrate how all common long chains should be made for the foundry; what is meant by common chains are all such as are composed of two strands of chain attached to a ring, or link, with hooks on the opposite ends ; in other words, like the one shown at Fig. 7, minus the turnbuckles. In all these there should be large links inserted at intervals, into which the hook 
• 
" eye," or take a " blackwall hitch"; so, be-cause it is easier to order a chain, with a measurable degree of certainty as to its fit-ness, than it is to procure the rope equivalent of the same, the former has become the rule now-a-days. Still this in no sense robs the rope of its merits; they are always useful adjuncts to foundry practice when it is practicable to ob-tain them. The single-spliced sling shown atFig. 17 can be made to serve many useful purposes such as drawing patterns, lifting cores, wood flasks, or anything which re-quires an uneven hitch to be made rapidly. Fig. 18 shows how readily it can be hitched fast to a ring and used for numberless pur-poses, either eud up, and Fig. 19 shows how a pair of light can hooks might be impro-vised at short notice. Fig. 20 illustrates the kind of eye to be used when rings, hooks or slings are to be secured thereon for the parpose of carrying heavy loads. Figs. 21 and 22 represent how to temporarily join two eyes or slings. Fig. 23 will serve to show how handily two or more single slings can be made useful in ways too numerous to mention, and Fig. 24 is a common hitch amongst riggers, its one excellent feature being that it can be made and unmade almost instantly. 
The great New York parades, celebrating the discovery of America by Columbps, four 
P ti I  pg-5
wheel is to be found in ROutgen's ples of Thermodynamics," translated by Prof. N. Jay Du Bois, Ph. D., and published in 1880 by John Wiley & Sons, of New York City, pages 587 to 596. The latter discussion is, however, too mathematical in its method for availability to the ordinary run of me-chanical readers. Moreover, the formulte given are based upon the fact that, in an engine running disconnected under full pressure, there will be in each revolution two points of maximum velocity in the fly-wheel, two points of minimum velocity, and four points at which the driving force equals the resistance of the fly-wheel to the increase of velocity. The consideration of the effect of variation in useful work to be performed is passed by without discussion. Prof. Jamieson's recent treatise on the steam en-gine contains the best discussion of the sub-ject I have yet seen in print, but this does not include the consideration of variation of useful work. The method which I have followed in these articles may be stated briefly—first, to find graphically the point or points of the stroke where the resistance overmasters the driving power ; second, to determine the excess of work of the resistance over that performed by the driving power during the interval of such overmastery; and third, to determine the weight of fly-wheel rim that will at a stated mean velocity perform the excess of 

crankshaft. It can also be shown anala-gously, that, with connecting rods of finite length (such t are ordinarily used), the rotative effort 6, the crank-pin varies ac-cording to ta different law. As it is not in-tended to give these articles a mathematical character, the discussion`-of the law govern-ing quantitatively the rotative effort on the crank-wrist will not be hereill attempted. I have, however, appended article a table which gives the coefficient of rotative effort for different points of strok,,: the crank angles and connecting rod angles'''for the different piston positions, and the press-ure on the slides for the same piston posi-tions, these data being tabulated for seven different ratios of connecting rod length to crank length. An illustration of the use of this table is given farther on. In the two cases previously discussed, the application of the resistance and of the driv-ing power at any point of the -stroke is always at the same crank angle, the multipli-cation of both these forces, each by the same quantity, does not alter the ratio existing be-tween them, and as, h e, the same result in determining the point the stroke where the resistance overmasters the driving power is obtained without consideration of the crank angle, the latter was omitted, as a useless complication in the graphic method used for those cases. It can be proved, moreover, that, although the spaces passed over respectively by the crank pin and the piston in any in-terval of time vary greatly throughout the stroke, the total work applied to rotation when the valves are driven directly or indirectly by the crankshaft and the work performed by the piston in the same interval of time, less the work of friction of the piston and stuffing box, are equal. The resistance to rotation of the useful work performed, and the fric-tion of the other parts, absorbs all the work delivered by the piston, less the work of the friction of the piston and 14%111111g box. Pronfithese considertitionm, it will be evidentale, in Abe graphic method ma-

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 Of two strands of chain attached to ti ring, or link, with hooks on the opposite ends ; in other words, like the one shown at Fig. 7, minus the turnbuckles. In all these there should be large links inserted at intervals, into which the hook could be inserted, as seen at A, Fig. 13; this increases the usefulness of the chain to a remarkable extent, as will be at once seen if the least thought is given to the subject. It would be well at this juncture to f call the attention of all concerned to a practice which, I am sorry to say, prevails in many of the foundries, of making the shop chains out of the old crane chains; now such practice is, to say the least, a very bad one, and there need be no wonder why, at such places. they should have so many broken chains, with 1111 occasional broken leg or back, to save the thing from becoming monotonous. When a chain is considered to be unfit for the crane it may be reasonably supposed that its usefulness is ended; and it should be at once consigned to the scrap pile. When a lift is to be taken on a very long box with two pairs of ordinary chains some-what short for the purpose, it is common to see one pair set to lift each end of the box ; this naturally spreads the rings in the hook after the manner shown at Fig. 14, and brings the strain front and back of the hook; the effect, not infrequently, of this mode is to rend the hook asunder. This may be ob viated in most cases by altering the position of the chains, so that each pair will lift one side; by so doing the spread takes place in the ring, as seen at Fig. 15, and the hook is called upon to beair the whole weight direct, without suffering any undue strain. But should it be absolutely necessary to take a lift which would in any way endanger the safety of the hook, let a screw clamp be made like the one shown at Fig. 16, and ap-plied as seen at A, Fig. 14. This will give stability to the hook and allow of such lifts being taken with comparative safety. Rope tackle is not as common in the foundries now as it used to be; this is not owing to any particular fault of such tackle, but because of the difficulty in procuring it in good shape. It is not every man who knows how to "splice" a rope, make an 
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C9 
A STUDY OF FLY-WHEELS. 
hundred years ago, were successful in all re-spects. Miles upon miles of men paraded, and miles upon miles of men and women lined the way. Such exhibitions help to stir up the embers of patriotism, and to keep alive love of country. 
 .1111111.•  
A Study of Fly-wheels.—IN. 
BY LEICESTER ALLEN. 
In the ninth edition of Bourne's " Treatise on the Steam Engine," printed twenty-four years ago, on page 150 he ,states that the problem of proportioning a fly-wheel to vary in velocity only within proposed limits " could easily be solved if we neglected the variation of resistance consequent upon a variation of velocity, and knew accurately the law according to which the pressure on the pi8ton and its velocity vary." Instead of discussing the subject from this truly scien-tific standpoint, he preferred, by calcula-tions based on results of empirical methods, to compute the weights of fly-wheels for various purposes to which steam engines are applied. The result is that he leaves the subject in a very unsatisfactory state of in-definiteness. Writers of more modern treatises have in many instances improved little on Mr. Bourne's treatment. A pretty full discus sion of the theory of the crank and the fly-
0 
work without a reduction of velocity below a stated predetermined limit. It has been shown in the second of this series of articles that, when the useful work opposes a constant resistance applied to the crank-pin during the stroke in the same manner as the steam piston applies its vary-ing power (the friction also being considered as constant), the point at which the driving power overmasters the power, and the excess of work over power for the rest of the stroke, or the work which, previously con-verted into living force in the fly-wheel, must, during the remainder of the stroke, be furnished by the fly-wheel, can be graph-ically determined. In the third article of the series it has been shown how, for a variable resistance applied to the crank in the same way that the variable power of the steam piston is applied, the same data are graphically ob tamable. It can be shown by trigonometrical meth-ods, combined with the theory of the com-position and resolution of forces, that when friction is assumed to be nothing, and when a force is applied by a connecting rod of infinite length to a crank-pin, the part of this force tending to cause rotation of the crank is found by multiplying the force by the sine of the angle included between the crank radius and the axis of the piston rod produced through the center of the 
111-1, 11111141. L IIU TONINLISIICIU LO IVIAL1011 CPI the useful work performed, and the fric-tion of the other parts, absorbs all the work delivered by the piston, less the work of the friction of the piston and stuffing box. From these considerations, it will be evident that in the graphic method em-ployed in the second and third articles, the point where the resistance overmasters 
the power in the stroke does not require the consideration of crank angles, as in both cases discussed the power and the resistance at any instant of the stroke are applied at the same crank angle. In this article is to be considered the case wherein power is delivered to the crank-pin or pins by different engines simultaneously at different crank angles, the common resultant of their driving power being opposed by a variable re-sistance differently applied. I may say here that the case of an engine in which a uniform or nearly uniform resistance is exerted by a belt or by gearing, this re-sistance always being in a direction at a right angle with a radius drawn from the center of the crankshaft through the point of application of the resistance is sufficiently dealt with in modern treatises on the steam engine, and that I have written the present articles to cover cases that, so far, have not been presented in the text-books, except, perhaps, in a manner too abstruse to meet the needs of those whose educational equip-ment does not include the higher mathe-matics. In fact, I have never seen a discus-sion of the case presented in the present article, if it has been treated at all, in any treatise on the steam engine, or in any work on mechanics. In order to present this case in as compli-cated a form as it is ever likely to occur, I will frame an example well calculated to illus-trate the principle and the method, though the relative positions of the different cranks, taken as an entire system, is one not the best adapted to the purpose, and one probably never met with in practice. I may remark, however, that the study of the effective pressure produced by co-opera-tive cranks in different and peculiar relative positions is to be strongly recommended as a means of gaining insight into all the charac-teristics of crank motion, and as a means of determining the most judicious relative po-

 

OCT 27 1892  PG-6 TOP and BOT you guess

0.05 0.10 0.20 0.30 0.40 0.50 0.60 0 70 0.80 0 90 0.95 
Crank Angle. 
22°54' 32° .47°54' 59' 70° 81°45' 92°15' 104°30' 119° 136°15' 1.)4"29' 
rt:J 0 
6°24' 8°54' 12° 4' 14°10' 15°34' 16°25' 16°35' 16°30' 11°24' 8°16' 

.Coeff. of Rotative Effort. 
0.453 0.112 0.674 0.157 0.877 0.214 0.987 0.252 1.035 0.278 1.023 0 294 0 988 0 298 0.896 0 296 0.749 0.257 0.546 0.202 0.342 0.145 
-6 0 ca 
22'54' 32°45' 47° 59° 70° 81°15' 92030' 104°30' 119° 136°15' 154°27' 
6 aO 0 P4 
6°24' 8°54' 12° 4' 14°10' 15°34' 16°25' 16°35' 16°30' 14°28' 11°24' 8°16' 
Coeff. of Rotative Effort. -1 
0.453 0 674 0.877 0.987 1.035 1.023 0.988 0.896 0.749 0.546 0.342 
0 S ,4; 0 0 
0.112 0.157 0 214 0.252 0.279 0.295 0.298 0.206 0.258 0.202 0.145 
9 - 
ai ca 
27°31' 33°30' 47°35' 59°30' 71° 82°30' 94° 106° 119°30' 138° 150° 
1► 
0 
6°38' 7°56' 10°38' 12°26' 13°40' 14°21' 14°26' 13°54' 12°34' 9°38' 7° 2' 
11 
0 
.14 Cl 0 0 
8 
0.565 0.668 0.865 0.974 1.024 1.025 0.928 0.878 0 761 0.533 0.391 
12 
0 
S 
0 
0 0 
0.116 0.139 0.188 0.220 0.243 0.256 0.257 0.247 0.223 0.170 0.123 
Crank Angle. 
28°25' 33'15' 48° 61° 71°45' 83°30' 95°30' 107° 121°15' 139° • 50°56' 
• 
Rod Angle. 
5° 4' 7° 9030' 11° 9' 12°11' 12°45' 12°47' 12°16' 11° 4' 8°23' 6°12' 
Coeff. of Rotative Effort. 
0.478 0.650 0 835 0.970 1.017 1.019 0.974 0.883 0.750 0.545 0.391 

0.088 0.123 0.167 0.197 0.216 0.226 0.227 0.217 0.196 0.147 0.109 
17 
Crank Angle. 
23°80' 33°30' 48°30' 61°15' 73°30' 84°30' 96°15' 107°15' 121.15' 139°15' 150°48' 
14 
53 S 0 
4034' 6°20' 8°36' 10° 7' 11° 3' 11°29' 11°28' 11° 1' 9°50' 7°30' 5°36' 

0.472 0.651 0 849 0.162 1 014 1.015 0.972 0.897 0.761 0.553 0.402 
0.080 0.111 0.151 0 178 0 195 0.203 0.203 0 195 0 173 0.132 0.098 
Crank Angle. 
23°58' 83°40' 49. 62° 74°15' 85° 96°30' 107°45' 121°30' 139°30' 151°44' 
6 71 S 0 
4°14' 5047' 7053' 9°14' 10° 5' 10026' 10°24' 9°58 8°55' 6°47' 4°58' 
NN 
Coeff. of Rotative Effort_ 
V4 I t 0 0 
0.474 0.074 0.646/3.101 0.853 0.138 0 9660.163 1 011 0.176 1 012 0.184 0.971 0.184 0.894 0.176 0.764 0.157 0.551'0.119 0.4000.087 
WI 
Crank Angle. 
23°45' 33°50' 50°15' 62°30' 74°45' 85°30' M°45' 108°15' 123° 139°30' 151051' 

Coeff. 
3°52' 0.464 0.068 0.95 5°17' 0.633 0.092 0 90 7°23' 0 851 0.130 0.80 8°30' 0.956 0.149 0.70 9°15' 1.007 0.163 0.60 9034' 1.010 0.169 0.50 9°32' 0.973 0.168 0.40 9° 6' 0.811 0 160 0.30 8° 2' 0.762 0.141 0.20 6°13' 0.567 0.109 0.10 4°30' 0.402 0.079 0.05 
ing shown at C Cl, 0 C2 and C U3, the scale of stroke line and all other parts of the figure being 8" = Ti", except the ordinates repre-senting pressures which are drawn to the scale -h" = 1 pound. The line r q is a vacu-um line in each diagram. Making due allowance for the pressure necessary to open the compressor valves, and drawing the diagram for adiabatic compres-sion of air, d e f g, and finding the indicated work by the method of ordinates commonly used in computing the work in indicator dia-grams, we get the total work of the compres-sionand discharge at each stroke, less the al-lowance for the clearance. It is 12,720 foot-pounds, the mean effective pressure being 20.25 pounds per square inch of the piston. If we consider that the friction of the com-pressor is ten per cent. of the work of com-pression and discharge, we shall find for the total work of compression 13,992 foot-pounds, including the friction of the com-pressor. Again, if we consider the friction of the two engines under load as ten per cent. of their total indicated power (an estimate that would be justified in a large number of cases where two engines Nkith their two stuffing boxes, having as-short a connection as is as-sumed, for these are used in the manner pro-posed), we shall find the total indicated work of the engines per stroke, including the total friction, to be 15,547 foot pounds. The useful work subtracted from this total work gives us the total work of friction per stroke. It is 2,827 foot-pounds. 
to be 15,547 foot-pounds, and 15,547 78.2 15)8.81 square inches, or the total steam pis-ton area required. As two steam pistons are assumed, each piston will require an area of 99.405 square inches. Their diameters will therefore be 111 inches. The area of each steam piston will be 0.3164 of the area of the compressor piston; hence every pound of pressure per square inch exerted on either of the steam pistons will exert only 0.3164 pound press-ure per square inch on the compressor piston. Now drawing the circle described by the crank pin centers, and indicating thereon the heretofore assumed relative positions of the cranks Cl C„ C3, and dividing the compres-sor diagram into ten equal parts by perpen-dicular ordinates erected from the points a, a2 a3, etc., on the stroke line d k, with the radius Cl d1 (radius of connecting rod), from each point a1 a2 a3, etc., draw small arcs cutting the crank-pin circle at points also indicated by al a2 a,, etc. The points of intersection of these arcs and the circle will be the crank-pin positions. corresponding to the piston positions indicated by the points a1 a2 a3 in the compressor diagram. Next, with radius equal to the distance be-tween the centers Ci and 612 draw short arcs cutting the crank circle from each of the points al a2 a3, etc., on the circle as centers. The points b,b2b3, where these arcs intersect the circle, will be positions of the crank C, corresponding to the piston positions al a2 a3, etc., on the compressor diagram. 
erected on the points b1 and ci in diagrams Si and 82 (corresponding piston positions of the steam pistons when the piston of the compressor is at al, on the line d k). Add these pressures (found to be 80 pounds per square inch for the diagram 8„ and 12 pounds per square inch for the diagram 82), and as we have found above that the press-ure exerted on each square inch of the com-pressor piston is 0.3164 of this, we have 92X 0.3164=29.1 pounds per square inch as the pressure exerted by the two steam pistons per square inch of the compressor piston. Do the same for each of the correlative points b2 and c,, b3 and c,, etc., and set down the results successively. In the present case we find that, when the coin-pressor piston is at the several points a1, a2, a3, etc., the steam engine pistons exert the following pressures per square inch of the compressor piston. At a1, 29.1 pounds. At a6, 15.47 pounds. At a2, 44.67 pounds. At a7, 11.00 pounds. At a3, 37.78 pounds. At a8, 8.20 pounds. At a4, 34.00 pounds. At a9, 3.05 pounds. At a5, 21.00 pounds. At the points al, a2, a3, etc., on the com-pressor diagram, erect from the friction line h i ordinates a, pi, a2,p2, a3, p3, etc., drawn to the scale of pressures, the pressures repre-sented by the ordinates to be those found as above ; that is, at a, erect an ordinate repre-senting 29.1 pounds ; at a an ordinate representing 44.67 pounds, and so on for all the points. It is generally advisable to de-termine an ordinate also for a point midway 
of rotative effort, as shown at diagram R in the figure, wherein the curve a b c is that of the rotative effort of the co-acting steam pis-tons, and the curve d e fis that of the rotative effort of the compressor, the line a c being the friction line, the friction being as above computed and considered as constant. If the graphic method be used, small errors in measurement will introduce a final error equal to or greater than the method I have explained, equal care being exercised in both cases. If the mathematical method be em-ployed, very exact results can be secured ; but as this involves very tedious calculations, involving the use of trigonometrical formulae, very few will think the increased accuracy a compensation for the increased labor. By the use of the table I have prepared, the points of the curves can be calculated by a simple arithmetical rule. All the coeffi-cients of rotative effort, and the coefficients of pressures on slides for different crank angles in the table, have been calculated by trigonometrical formulae, so that for connect-ing rods of the ordinary lengths in proportion to crank, the following arithmetical rules will apply. Rule 1.-To find the rotative effort per square inch of a piston of a single engine, at any of the crank angles given in the table : Find from a diagram the pressure per square inch at the piston position given in the table, and multiply this pressure by the coefficient of rotative effort correspond-ing with the ratio of rod radius to crank ra-dius, as also indicated in the table. 

**************7777777777777777777777777777777777777777777777777**********

0.05 0.10 0.20 0.30 0.40 0.50 0.60 0 70 0.80 0 90 0.95 
Crank Angle. 
22°54' 32° .47°54' 59' 70° 81°45' 92°15' 104°30' 119° 136°15' 1.)4"29' 
rt:J 0 
6°24' 8°54' 12° 4' 14°10' 15°34' 16°25' 16°35' 16°30' 11°24' 8°16' 

.Coeff. of Rotative Effort. 
0.453 0.112 0.674 0.157 0.877 0.214 0.987 0.252 1.035 0.278 1.023 0 294 0 988 0 298 0.896 0 296 0.749 0.257 0.546 0.202 0.342 0.145 
-6 0 ca 
22'54' 32°45' 47° 59° 70° 81°15' 92030' 104°30' 119° 136°15' 154°27' 
6 aO 0 P4 
6°24' 8°54' 12° 4' 14°10' 15°34' 16°25' 16°35' 16°30' 14°28' 11°24' 8°16' 
Coeff. of Rotative Effort. -1 
0.453 0 674 0.877 0.987 1.035 1.023 0.988 0.896 0.749 0.546 0.342 
0 S ,4; 0 0 
0.112 0.157 0 214 0.252 0.279 0.295 0.298 0.206 0.258 0.202 0.145 
9 - 
ai ca 
27°31' 33°30' 47°35' 59°30' 71° 82°30' 94° 106° 119°30' 138° 150° 
1► 
0 
6°38' 7°56' 10°38' 12°26' 13°40' 14°21' 14°26' 13°54' 12°34' 9°38' 7° 2' 
11 
0 
.14 Cl 0 0 
8 
0.565 0.668 0.865 0.974 1.024 1.025 0.928 0.878 0 761 0.533 0.391 
12 
0 
S 
0 
0 0 
0.116 0.139 0.188 0.220 0.243 0.256 0.257 0.247 0.223 0.170 0.123 
Crank Angle. 
28°25' 33'15' 48° 61° 71°45' 83°30' 95°30' 107° 121°15' 139° • 50°56' 
• 
Rod Angle. 
5° 4' 7° 9030' 11° 9' 12°11' 12°45' 12°47' 12°16' 11° 4' 8°23' 6°12' 
Coeff. of Rotative Effort. 
0.478 0.650 0 835 0.970 1.017 1.019 0.974 0.883 0.750 0.545 0.391 

0.088 0.123 0.167 0.197 0.216 0.226 0.227 0.217 0.196 0.147 0.109 
17 
Crank Angle. 
23°80' 33°30' 48°30' 61°15' 73°30' 84°30' 96°15' 107°15' 121.15' 139°15' 150°48' 
14 
53 S 0 
4034' 6°20' 8°36' 10° 7' 11° 3' 11°29' 11°28' 11° 1' 9°50' 7°30' 5°36' 

0.472 0.651 0 849 0.162 1 014 1.015 0.972 0.897 0.761 0.553 0.402 
0.080 0.111 0.151 0 178 0 195 0.203 0.203 0 195 0 173 0.132 0.098 
Crank Angle. 
23°58' 83°40' 49. 62° 74°15' 85° 96°30' 107°45' 121°30' 139°30' 151°44' 
6 71 S 0 
4°14' 5047' 7053' 9°14' 10° 5' 10026' 10°24' 9°58 8°55' 6°47' 4°58' 
NN 
Coeff. of Rotative Effort_ 
V4 I t 0 0 
0.474 0.074 0.646/3.101 0.853 0.138 0 9660.163 1 011 0.176 1 012 0.184 0.971 0.184 0.894 0.176 0.764 0.157 0.551'0.119 0.4000.087 
WI 
Crank Angle. 
23°45' 33°50' 50°15' 62°30' 74°45' 85°30' M°45' 108°15' 123° 139°30' 151051' 

Coeff. 
3°52' 0.464 0.068 0.95 5°17' 0.633 0.092 0 90 7°23' 0 851 0.130 0.80 8°30' 0.956 0.149 0.70 9°15' 1.007 0.163 0.60 9034' 1.010 0.169 0.50 9°32' 0.973 0.168 0.40 9° 6' 0.811 0 160 0.30 8° 2' 0.762 0.141 0.20 6°13' 0.567 0.109 0.10 4°30' 0.402 0.079 0.05 
ing shown at C Cl, 0 C2 and C U3, the scale of stroke line and all other parts of the figure being 8" = Ti", except the ordinates repre-senting pressures which are drawn to the scale -h" = 1 pound. The line r q is a vacu-um line in each diagram. Making due allowance for the pressure necessary to open the compressor valves, and drawing the diagram for adiabatic compres-sion of air, d e f g, and finding the indicated work by the method of ordinates commonly used in computing the work in indicator dia-grams, we get the total work of the compres-sionand discharge at each stroke, less the al-lowance for the clearance. It is 12,720 foot-pounds, the mean effective pressure being 20.25 pounds per square inch of the piston. If we consider that the friction of the com-pressor is ten per cent. of the work of com-pression and discharge, we shall find for the total work of compression 13,992 foot-pounds, including the friction of the com-pressor. Again, if we consider the friction of the two engines under load as ten per cent. of their total indicated power (an estimate that would be justified in a large number of cases where two engines Nkith their two stuffing boxes, having as-short a connection as is as-sumed, for these are used in the manner pro-posed), we shall find the total indicated work of the engines per stroke, including the total friction, to be 15,547 foot pounds. The useful work subtracted from this total work gives us the total work of friction per stroke. It is 2,827 foot-pounds. 
to be 15,547 foot-pounds, and 15,547 78.2 15)8.81 square inches, or the total steam pis-ton area required. As two steam pistons are assumed, each piston will require an area of 99.405 square inches. Their diameters will therefore be 111 inches. The area of each steam piston will be 0.3164 of the area of the compressor piston; hence every pound of pressure per square inch exerted on either of the steam pistons will exert only 0.3164 pound press-ure per square inch on the compressor piston. Now drawing the circle described by the crank pin centers, and indicating thereon the heretofore assumed relative positions of the cranks Cl C„ C3, and dividing the compres-sor diagram into ten equal parts by perpen-dicular ordinates erected from the points a, a2 a3, etc., on the stroke line d k, with the radius Cl d1 (radius of connecting rod), from each point a1 a2 a3, etc., draw small arcs cutting the crank-pin circle at points also indicated by al a2 a,, etc. The points of intersection of these arcs and the circle will be the crank-pin positions. corresponding to the piston positions indicated by the points a1 a2 a3 in the compressor diagram. Next, with radius equal to the distance be-tween the centers Ci and 612 draw short arcs cutting the crank circle from each of the points al a2 a3, etc., on the circle as centers. The points b,b2b3, where these arcs intersect the circle, will be positions of the crank C, corresponding to the piston positions al a2 a3, etc., on the compressor diagram. 
erected on the points b1 and ci in diagrams Si and 82 (corresponding piston positions of the steam pistons when the piston of the compressor is at al, on the line d k). Add these pressures (found to be 80 pounds per square inch for the diagram 8„ and 12 pounds per square inch for the diagram 82), and as we have found above that the press-ure exerted on each square inch of the com-pressor piston is 0.3164 of this, we have 92X 0.3164=29.1 pounds per square inch as the pressure exerted by the two steam pistons per square inch of the compressor piston. Do the same for each of the correlative points b2 and c,, b3 and c,, etc., and set down the results successively. In the present case we find that, when the coin-pressor piston is at the several points a1, a2, a3, etc., the steam engine pistons exert the following pressures per square inch of the compressor piston. At a1, 29.1 pounds. At a6, 15.47 pounds. At a2, 44.67 pounds. At a7, 11.00 pounds. At a3, 37.78 pounds. At a8, 8.20 pounds. At a4, 34.00 pounds. At a9, 3.05 pounds. At a5, 21.00 pounds. At the points al, a2, a3, etc., on the com-pressor diagram, erect from the friction line h i ordinates a, pi, a2,p2, a3, p3, etc., drawn to the scale of pressures, the pressures repre-sented by the ordinates to be those found as above ; that is, at a, erect an ordinate repre-senting 29.1 pounds ; at a an ordinate representing 44.67 pounds, and so on for all the points. It is generally advisable to de-termine an ordinate also for a point midway 
of rotative effort, as shown at diagram R in the figure, wherein the curve a b c is that of the rotative effort of the co-acting steam pis-tons, and the curve d e fis that of the rotative effort of the compressor, the line a c being the friction line, the friction being as above computed and considered as constant. If the graphic method be used, small errors in measurement will introduce a final error equal to or greater than the method I have explained, equal care being exercised in both cases. If the mathematical method be em-ployed, very exact results can be secured ; but as this involves very tedious calculations, involving the use of trigonometrical formulae, very few will think the increased accuracy a compensation for the increased labor. By the use of the table I have prepared, the points of the curves can be calculated by a simple arithmetical rule. All the coeffi-cients of rotative effort, and the coefficients of pressures on slides for different crank angles in the table, have been calculated by trigonometrical formulae, so that for connect-ing rods of the ordinary lengths in proportion to crank, the following arithmetical rules will apply. Rule 1.-To find the rotative effort per square inch of a piston of a single engine, at any of the crank angles given in the table : Find from a diagram the pressure per square inch at the piston position given in the table, and multiply this pressure by the coefficient of rotative effort correspond-ing with the ratio of rod radius to crank ra-dius, as also indicated in the table. 

 
to be 15,547 foot-pounds, and 15,547 78.2 15)8.81 square inches, or the total steam pis-ton area required. As two steam pistons are assumed, each piston will require an area of 99.405 square inches. Their diameters will therefore be 111 inches. The area of each steam piston will be 0.3164 of the area of the compressor piston; hence every pound of pressure per square inch exerted on either of the steam pistons will exert only 0.3164 pound press-ure per square inch on the compressor piston. Now drawing the circle described by the crank pin centers, and indicating thereon the heretofore assumed relative positions of the cranks Cl C„ C3, and dividing the compres-sor diagram into ten equal parts by perpen-dicular ordinates erected from the points a, a2 a3, etc., on the stroke line d k, with the radius Cl d1 (radius of connecting rod), from each point a1 a2 a3, etc., draw small arcs cutting the crank-pin circle at points also indicated by al a2 a,, etc. The points of intersection of these arcs and the circle will be the crank-pin positions. corresponding to the piston positions indicated by the points a1 a2 a3 in the compressor diagram. Next, with radius equal to the distance be-tween the centers Ci and 612 draw short arcs cutting the crank circle from each of the points al a2 a3, etc., on the circle as centers. The points b,b2b3, where these arcs intersect the circle, will be positions of the crank C, corresponding to the piston positions al a2 a3, etc., on the compressor diagram. 
erected on the points b1 and ci in diagrams Si and 82 (corresponding piston positions of the steam pistons when the piston of the compressor is at al, on the line d k). Add these pressures (found to be 80 pounds per square inch for the diagram 8„ and 12 pounds per square inch for the diagram 82), and as we have found above that the press-ure exerted on each square inch of the com-pressor piston is 0.3164 of this, we have 92X 0.3164=29.1 pounds per square inch as the pressure exerted by the two steam pistons per square inch of the compressor piston. Do the same for each of the correlative points b2 and c,, b3 and c,, etc., and set down the results successively. In the present case we find that, when the coin-pressor piston is at the several points a1, a2, a3, etc., the steam engine pistons exert the following pressures per square inch of the compressor piston. At a1, 29.1 pounds. At a6, 15.47 pounds. At a2, 44.67 pounds. At a7, 11.00 pounds. At a3, 37.78 pounds. At a8, 8.20 pounds. At a4, 34.00 pounds. At a9, 3.05 pounds. At a5, 21.00 pounds. At the points al, a2, a3, etc., on the com-pressor diagram, erect from the friction line h i ordinates a, pi, a2,p2, a3, p3, etc., drawn to the scale of pressures, the pressures repre-sented by the ordinates to be those found as above ; that is, at a, erect an ordinate repre-senting 29.1 pounds ; at a an ordinate representing 44.67 pounds, and so on for all the points. It is generally advisable to de-termine an ordinate also for a point midway 
of rotative effort, as shown at diagram R in the figure, wherein the curve a b c is that of the rotative effort of the co-acting steam pis-tons, and the curve d e fis that of the rotative effort of the compressor, the line a c being the friction line, the friction being as above computed and considered as constant. If the graphic method be used, small errors in measurement will introduce a final error equal to or greater than the method I have explained, equal care being exercised in both cases. If the mathematical method be em-ployed, very exact results can be secured ; but as this involves very tedious calculations, involving the use of trigonometrical formulae, very few will think the increased accuracy a compensation for the increased labor. By the use of the table I have prepared, the points of the curves can be calculated by a simple arithmetical rule. All the coeffi-cients of rotative effort, and the coefficients of pressures on slides for different crank angles in the table, have been calculated by trigonometrical formulae, so that for connect-ing rods of the ordinary lengths in proportion to crank, the following arithmetical rules will apply. Rule 1.-To find the rotative effort per square inch of a piston of a single engine, at any of the crank angles given in the table : Find from a diagram the pressure per square inch at the piston position given in the table, and multiply this pressure by the coefficient of rotative effort correspond-ing with the ratio of rod radius to crank ra-dius, as also indicated in the table.

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OCT 27 1892  PG-7 TOP and BOT  YEA

MACHINIST 
If pressure on slides per square inch of piston is desired, use in the above rule the coefficient of pressure on slides, instead of the coefficient of rotative effort. Rule 2.—To find the combined rotative effort per square inch of two or more co-act-ing engines, with cranks set at the same or at different angles. Find the total pressure on each piston at its respective piston position corresponding with the angle through which its crank has rotated from the beginning of the stroke. Multiply this pressure by the coefficient of rotative pressure taken from the table, as directed in Rule 1. Add the products to-gether, and divide the sum by the sum of the areas of the pistons. The quotient will be the rotative effort per square inch exerted simultaneously by all the pistons at their respective positions. Note a.—The table is constructed for both the forward and backward stroke of the en-gine. If rotative effort for backward stroke be desired, the piston position must be taken from the right-hand column of the table. Note b.—If rotative effort for points in-termediate between any two of the piston positions given in the table are desired, it will be sufficiently accurate for the pur-pose of computing fly-wheels, to find the difference between the coefficients corre-sponding to the two piston positions, and add to the lesser or subtract from the greater of the two coefficients such a fraction of this difference as corresponds to the differ-ence of position ; thus, for a point midway between 0.30 and 0.40 of the forward stroke for a connecting rod 4 times the length of the crank, the coefficient of rotative effort for position 0.30 is 0.974, and for position 0.40 it is 1.024. The difference between these coefficients is 0.050, and half this differ-ence is 0.025, which, either subtracted from 1.024 or added to 0.974, gives 0.999. By these rules the rotary effort for the different positions per square inch of the air pressure plus the friction pressure, trans-mitted to the crank Ci, having been obtained, the curve d e f traced through the upper extremities of ordinates erected on the fric-tion line a c, and representing this effort at ciifl'erer positions, was obtained for dia-gram P. Similarly finding the rotative effort per S41111111' 1111'11 1.1)1'.41111'11 of the steam engine pis 
a case it is necessary to construct reverse diagrams both for the resistance and the driving force, as shown below the stroke line or atmospheric line d k in the air compres-sor diagram, and find the curve of the driv-ing power for that side also. In such a case the area representing the work which the fly-wheel must supply will lie partly above and partly below the stroke line. 
LETTERS FROM PRACTICAL MEN. 
Centrifugal Action in Ropes and Belts. Editor American Machinist : The article on " Centrifugal Action in Ropes and Belts," by " M. E.," in the AMERI-CAN MACHINIST for September 17, 1892, gives a good example of the value of plotted curves. The writer has not, however, gone into the problem as far as seems desirable, and his reasoning and results may be im-proved. The phrase, !` absorption of power," which lie uses, is an unfortunate one in this place, as the centrifugal action does not ab-sorb or occasion a loss of power. The ten-sion required in the belt or rope to balance the centrifugal forces does lower the maxi-mum net or effective tension, but the extent 
Power Curves Double Leodher Belt S,5 =150 lbs, • 93.75 lbs. • 4 W=.25 lbs. 

Let Sn = the tension on tight side when slip is impending, Let So = the tension on slack side when slip is impending, Let E = net or effective tension, Let w = weight of belt per inch wide and per foot long, Let g = acceleration due to gravity, Let v = velocity of belt in feet per second, dLet C = the ratio determinable by experi-ment. Then the centrifugal tension is w V2 per 9 
inch width of belt. Sn w v2   9„ = C (1); Sn -I- So = 2 T. (2) So w v. From these two equations we find: 2 C T — (C —1)w V2  
Sn 
1 + C 2 T (C — 1 ) V 2 So-   (4) 1 + C And from (3) and (4) the net tension E =- Sn—So =2 CY 1 T —w V2) 1 (5) 
(3) 

20 40 60 80 100 Velocity feet per second 
Power Curves Rope. S = 215 it, 'F 12U its. 

55 
50 
45 5 40 35 hk 80 ,t2, 25 20 p?, 15 104 
90 80 70 
5 
0 
o. (9) 
 s to violate lowable tensi f`' ” Tv the origi-this result a (3) 
Tv = 

7 
ting by produce Equation 
Sm (1 + + (C — 1)T112_ 
2C 
. (6) 
Hence Tv may be greater as v is greater, the tension Sin not being exceeded; and Tv exceeds the quantity Tat slow speeds by C — 1 w e 77x (7) 2C g which is always less than one-half the cen!--• trifugal tension. The net or effective 
tension obtained is, then, Ev = 2 C — 1 
C + 1 (Tv — w v2) [from (5)]. The effective ten-sion is then greater than if no extra tension Tx were imposed by 2 (C — 1) C — 1 C+1 2C tr v2 (C— 1)2 w v2 C (C ± 1) It is to be noted in this case that if the belt is to pull its full resistance when start-ing from rest, the tension will be exceeded on the tight side by the q tity Tx. It is also to be noted that the pressure on the shaft bearings at running speed is less than when standing by double the centrifu-gal- tension, so that the extra tension Tx is more than offset, as far as pressure on the bearings is concerned. By examining the curves drawn below, it will be seen that by means of the extra ten-sion Tx the maximum power from the 1" rope is 17.5 H. P. at about 82 feet per sec-ond, as against 14 H. P. at 67 feet per sec-ond when this tension is not imposed; and similar results are seen in the case of the leather belt. ALBERT KINGSBURY. 
r 
About Governors. Editor American Machinist : Not long since I was so fortunate as to be present at a gathering of gentlemen in which the central figure was a lawyer who prided himself on his literary taste and conversa-tional powers. Touching on the wonderful strides of sa-il* ence and invention, he said : "Why, they now have governors which 111.11 be applied to tIn gnu pipes in (►lir howses, which Ilit, supply I Os Ito HIlit 

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differen in positions per square inch of I,Iw air pressure plus the friction pressure, trans-mitted to the crank C,, having been obtained, the curve d e f traced through the upper extremities of ordinates erected on the fric-tion line a c, and representing this effort at different positions, was obtained for dia-gram P. Similarly finding the rotative effort per square inch for each of the steam engine pis-tons, at points simultaneously occupied by them when the compressor piston is success-ively at the points a1 a2 a3, etc., adding these efforts, and multiplying the sum by 0.3164 (this being the pressure above found on the compressor piston per square inch for each pound of pressure exerted on either of the steam pistons), we get the ordinates of opposite combined rotary effort for the two steam pistons, and laying these off through the same points from the friction line a c in diagram R we get the curve of rotative effort opposed to the rotative effort of the com-pressor. These lines of rotative effort cross at w1, which corresponds with the position w in the diagram below it very nearly, as can be seen. But as in the method used we have neglected weight of all but the rims of fly-wheels, the stored-up force in the parts so neglected will more than compensate for this slight discrepancy. The difference between the mean rotative effort of the compressor piston and the com-bined mean rotative effort of the steam pis tons from the point w, to the end of the stroke multiplied into the product of the area of the compressor piston and the distance trav-ersed by the crank-pin to the end of the stroke, after w, is reached, will give the total work to be supplied at each stroke by the fly-wheel after the resisting force overmas-ters the driving force, and when this is ob-tained the weight of the fly-wheel rim is to be computed, as prescribed in the former article. Lastly, it may happen that the point where the driving force overmasters the resistance may not be at the beginning of the stroke, as in the cases I have discussed, and it may oc-cur, also, that this event may occur during one stroke, while the point at which the re-sistance next overmasters the driving force occurs during the opposite stroke, In such 
Power Curves Rope. sin = 215 lbs. T.129 lbs. C= 5 W=.322 lbs. 

so 
70 
6 
d   II •V laM1111111.   ■   1011■■► 120 110 
20 
10 60 80 1 0 Velocity feet per second IN ROPES 
CENTRIFUGA.L ACTION 
to which it does this is not so simply deter-mined as " M. E." would have us believe. His assumption that the net or effective ten-sion is lowered by the exact amount of the centrifugal tension is unfounded, and is er-roneous, except for a special case, as will be shown. We may prose upon the common as-sumption that, as long as the belt is in con-tact with both pulleys, the sum of the ten-sions in the tight and the slack sides is a con-stant quantity, equal to twice that existing in either side when the two are equal. If the driving pulley be turned until slipping is impending, the tension on the tight side will exceed the original tension, and that on the slack side will fall short of it by an equal amount, and there will then exist between the tensions a ratio depending upon the angle of contact and the coefficient of friction. The difference between the two tensions is the " net " or effective " tension. Now if a portion of each tension, equal on the two sides, is needed to balance the coarifugal forces, the ratio mentioned will Alist be-tween the remaining portions only. In symbols : Let T = the equal initial tensions per inch of width, 
AND 
20 
10 
5 
.0 
BELTS. 
If v = o, then the net tension is 2 C — 1 C + 1 T; and for any other speed the amount to be subtracted from this " nominal effective tension " is 2 C — 1 . w v$ Ifthe ratio C C ± 1 g = 3, which is a ratio which may exist with leather belts and iron pulleys, then the co-efficient 2 C — 1 is equal to unity, and the C +1 effective tension is reduced by the amount of the centrifugal tension, w v2. But if C equal any other number, the reduction will be greater or less than w v2, according as C is greater or less than 3. We have values of C in practice as low as 1.6, and as high as 6. Taking the former figure, the reduction is 12 w v2 ; and the latter,  10 w v2 26 g 7 A consideration of some importance is symbolized in Equation (3). Since C is always greater than unity, if T be a fixed quantity the tension Sr, decreases as v in-creases, and So increases by an equal amount, as seen in Equation (4). Evidently if the speed be known, T may be made such as to produce a tension Sn = Sm, the highest al-
411/, II/11A 1.1.11. I I V'', Mr WI I lin pr,1 1111.5(.111, gial►eling or gentlemen in which the central figure was a lawyer who prided himself on his literary taste and conversa-tional powers. Touching on the wonderful strides of sci-ence and invention, be said : "Why, they now have governors which can be applied to the gas pipes in our houses, and which regu-late the supply of gas to suit the number of burners in use, and its action is identically the same in principle as that of the governor used on steam engines. There you know they have those two balls that hang by arms and revolve rapidly when the engine is in motion. Now they are used to regulate the pressure of steam, and are so arranged that when the pressure is just right the balls re-main in one position, but when it gets too high it pushes a valve and thus raises the balls up, and in so doing expends its surplus energy. In this way the pressure is kept constant and the speed never varies." I listened, but said nothing, and some one asked how it acted when the pressure became too low ? " Oh, you see," he replied, " the balls then have an opposite effect by pressing down OD the steam and increasing its power." A. S. MALLORY. 416 Broadway, Camden, N. J. 
Cutting- Cams. Editor American Machinist : I shall be glad if Mr. C. F. Smith can show me how he can cut a cam on his de-vice—illustrated in your issue of October 13th inst—and have the cam come from the machine so that it will oscillate a lever with-out loose spots or " sticks. He will remem-ber, of course, that the roller will (*scribe an arc, and be a part of the time above the center of the cam, and a part below it, and he will see that this necessitates that the said roller cannot work well in a groove that is cut with a tool which operates radially, or at any constant tangent, the whole revolution. A. D. PENTZ. 
•41111N1  After a fairly long trial the plan of double-screw—end and end—ferry-boats on the North River • has, so it appears, proved a success. These boats are said to be a little more eco-nomical than side-wheel boats, and in every way more convenient. 
 

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OCT 27 1892  PG-8 TOP and BOT

Communications relating to the reading columns should be addressed to the Editor. All other com-munications should be addressed : AMERICAN MACHINIST, 203 BROADWAY, NEW YORK. 
PUBLISHED WEEKLY AT 2C3 Broadway, New York. 
HORACE 13. MILLER. Pres't and Bus. Manager. I -CURGUS B. MooRE, Treas. and Sec'y. 
F F. HEMENWAY, Editor and Mech. Engineer. J. G. A. MEYER, FRED J. MILLER, Associates. 
Special Announcements. CV— Positively we will neither publish anything in our reading columns for pay or in consideration, of advertising patronage. Those who wish to recommend their wares to our readers can do so as fully as they choose in our advertising columns, but our editorial opinions are not for sale. We jive no premiums to secure either subscribers or advertisers. CAr Every correspondent, in order to insure atten-tion, should give his full name and address, not for publication, but as a guarantee of good faith. r--— We are not engaged in procuring patent rights, or in selling machinery, nor have we any pet scheme to advance, or hobby to ride. We invite correspondence from practical ma-chinists, engineers, inventors, draftsmen, and all those specially interested in t occupations we represent, * on subjects pertaining to chinery. it-— Subscribers can h e the mailing address of their paper changed as often as they desire. Send both old and new addresses. Those who fail to receive their papers promptly will please notify us at once. Date on wrapper denotes week with which subsmiption expires. 
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The American News Company, Publishers' Agents, New York. DEALERS SUPPLIED BY The Albany News Company, Albany, N. Y. The American News. Company, New York, N. Y. The Baltimore News Company, Baltimore, Md. The Brooklyn News Company, Brooklyn, N. Y. The Buffalo News Co., Buffalo, N. Y. The Central News Company, Philadelphia, Pa. The Cincinnati News Company, Cincinnati, Ohio. The Cleveland News Company, Cleveland, Ohio. The Colorado News Company, Denver, Colorado. The Detroit News Company, Detroit, Mich. The International News Company,New York, N. Y. The Minnesota News Company, St. Paul, Minn. The Montreal News Company, Montreal, Canada. The National News Company, New York, N. Y. The Newark News Company, Newark, N. J. The New England News Company, Boston, Mass. The Now Orleans News Company, New Orleans, La. The New York News Company, New York, N. Y. The Northern News Company, Troy, New York. The Omaha News company, ()maim, Nob. The l'IttsbarKh News Company,Pittsburuh, Pa. IL 1. 
Transportation of Crowds. 
A notable exception to the gener'' among the transportation compani° 3e duty it became to handle the vast crowds visiting this city recently was observed in the case of the Central Railroad of New Jer-sey, which, instead of reducing the number of its boats, towards midnight of the 12th, kept them all running, with the full force of ticket takers on duty, so that, though some passengers were unavoidably delayed, owing to the tremendous crowds, there was no un-necessary or unavoidable delay. We should think that the managers of some of the other companies would feel somewhat ashamed of their management of the affair. They knew that their trains and boats had been crowd-ed heavily all day by a vast throng of people coming into the city to see the day and even-ing parades. Extra trains were run and extra cars were attached to regular trains. It would seem as though a child ought to have known that these people would want to get out of the city all at once, just as soon as the spectacle was over, and that extra facilities should be provided for their doing so. In-stead of providing these they tied up most of their boats, running the others at about half-hour intervals, while the crowds became almost mobs and women fainted by the dozen from the crowding and lack of air. The whole performance was decidedly dis-creditable, and brings to mind the utter col-lapse of the roads' arrangements during the occasion of the Christian Endeavor meeting here last summer. In that case the number of people brought into the city was far in ex-cess of what was expected, and the arrange-ments for stamping, signing and otherwise "fixing up" the return tickets were soon shown to be utterly inadequate. Roads that had a. dozen or more offices in the city would allow the tickets to be signed by the holders and stamped in only one of these offices, and that office often the most inconveniently lo-cated one with respect to the road over which the people were to leave. Some of the roads gave up n11 their requirements, printed 011 1,111' bad( 0 I' the I ielwt,si in it siring as long as the moral law, find mImply told the e„ thy trains atmd promint their 
he three days. I. ery hour of the day 3arly thirty-three s were run on each road—an average ore than one train every thirty seconds on the four roads. The amount received for fares during the three days was $146,076.85. Directions for Operating Machinery. 
There is perhaps no one feature of the ma-chine business which is more bothersome to manufacturers than that connected with the matter of giving directions for the successful operation of their machines and then finding that these directions are utterly ignored by the purchaser, who promptly complains of the machine, nevertheless,when it fails to per-form exactly as represented; such failure in nine cases out of ten resulting directly from the failure to follow directions. This ap-plies with especial force to machines which are more or less out of the usual line, and with which it is not to be supposed that all mechanics into whose hands they may fall can know all about them and their manage-ment, as they might a lathe, a tilaner, or a drill press. When a mechanic invents and develops a new machine he usually finds out a lot of things about it in the course of his experi-menting,which neither he nor any one else can know intuitively or in any other way than by similar experimenting, which experi-menting of yen costs much in time and money. Being vitally interested in the successful working of this machine after it is in the hands of the user, he takes some pains to make a clear statement of the conditions un-der which the machine may be expected to work satisfactorily, this statement naturally taking the form of directions for its ope tion. If it is a machine which must be pipe when in place, he has found by actual experi-ence that if piped in a certain way it will not work satisfactorily, while if piped in another way it will work perfectly. He may have, discovered that a certain oil will answer the purpose, and that no other of the commonly employed lubricants can be depended upon at all. His directions specify the proper meth-od of piping and the proper lubricant, and his deep disgust may be imagined, when, on revelvitor n mond-idol, of the toniakilltitt he 
to think that this is all nonsense, and that the oil which he is using on the other ma-chinery about the plant will do as well. He thinks that he probably knows as much about the proper lubrication of machinery as the manufacturer, and so he may, in a gen-eral way, though he has not had experience with this particular device. If he does not choose to take the manufacturer's word for it, he can only learn by an expensive trial, which might be avoided in many cases, we think, if there was, with the directions, some explanation, or at least some indication that other oils had been thoroughly tried, and that the specification of a certain one was something more than a mere notion or a whim. Mechanics and engineers usually like to act from intelligent motives. If they must use a certain oil and no other, they at least want some rational reason for so doing, and dislike to use it simply because some other man declares they must. This only shows that human nature may be studied with profit in writing directions for the use of machinery as well as in other matters. 

iS It Going Back ? 
Years ago bold men were accustomed to hunt the grisly bear with a gun that was hardly more than .32 caliber. It was considered rather dangerous sport, however. After that came the gun of larger caliber, which was adopted, as a rifle, for army use by most civilized countries. Just now there is an evident intention to go back to guns of small caliber—.30 or even less. This move, which is being considered by the United States government, is probably due to a consideration of the use of magazine guns, the smaller caliber making them more con-venient. When a man in battle gets hit with a .30 bullet, the probabilities are that, if not killed, he will go out of action, which amounts to about the same thing. The small caliber rifle may mean a step in ad-vance, instead of the contrary. Recent ex-periments seem to prove that it has greater range. 
 

Cast-iron. 
During the last ten or fifteen years manu-******************************************888888888888888810---10---120---888888888888888888888888888888888888888*************************

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The International News Company, BREAM'S BLDG'S, Chancery Lane, LONDON, E. C. ENG., or Stefanstrasse 18, LEIPZIG, GERMANY, will receive subscriptions for the AMERICAN MACHINIST, at 16/6 per annum, English currency, or 17 marks per annum, German currency, postpaid. Subscriptions received in Paris, France, by E. TERQUEM, 31 Boulevard Hausmann, at 20 francs per annum, postpaid. Subscriptions received in Australia by W.WILLIAMS, 37 and 21 Fink's Buildings, Melbourne. 
NEW YORK, OCTOBER 27, 1892. 
CONTENTS. 
PAGE Taper Rolling Machine ..... 1 The Cook Automatic Nut-tapping Machine  1, 2 Barnaby's Compression Coupling  2 Cogging Wheels. By Joseph Horner.  2, 3 Metal Flask Pins  3 A New Double-tube Injector   3 Novel Measuring of Water Depths   3 Self-closing Water Gauge  3 New Flue Welder 
Chains, Beams, Slings, Hooks, Ropes, Etc., for Lifting and Handling All Classes of Work in the Foundry. By S. Bolland  4, 5 A Study of Fly-wheels. By Leicester Allen...5, 6, 7 Letters from Practical Men : Centrifugal Ac-tion in Ropes and Belts. By Albert Kings-bury.... About Governors. By A. S. Mallory ....Cutting Cams. By A. D. Pentz  7 Transportation of Crowds    8 Directions for Operating Machinery  8 Is It Going Back?.   8 Cast-iron   8 Literary Notes    8, 9 Questions and Answers.   9 An Important Time With a Foreman and a Workman — Prudence and Crotchets. By Jarno  9, 10 Foreign Paper Money.    10 A Corkscrew Railroad   10 Manufactures    10, 11 Machinists' Supplies and Iron   ..... 11 
W the tici«.tm b) be signed by t b►lders and stamped ill only 0110 of these offices, and that office often the most inconveniently lo-cated one with respect to the road over which the people were to leave. Some of the roads gave up all their requirements, printed on the back of the tickets in a string as long as the moral law, and simply told the people to get onto the trains and present their tickets without stamping or signature, and altogether it was about the worst mixed af-fair that could have been well devised. It is safe to say that if the mechanical depart-ments of these roads should become so com-pletely demoralized as were the traffic de-partments in this emergency, the men re-sponsible for it would never have heard the last of it. 
The elevated roads of this city broke all previous records for number of passengers carried during the week of festivities, the heaviest business being done on Wednesday, when 1,075,537 people were carried in the twenty-four hours. This not only beats all previous records by this road, but all records of all roads; no other road in the world carrying as many passengers as this, either regularly or on special occasions. The ele-vated roads are always operated at so near their maximum capacity that it was not to be expected that the vast crowds in the city during this occasion could be transported without much delay and discomfort, but nevertheless we think that any one at all ac-quainted with railroad operating must con-cede that the management of the roads was admirable—there were no accidents, and there was as little discomfort or delay as could have been expected in view of the relation between the normal capacity of the roads and the crowds to be carried. The following interesting statement has been prepared, to give an idea of the tremendous proportion of the traffic. Estimating that each train was crowded, it would hold fully 300 persons. Therefore it would require at least 9,738 crowded trains. But at some hours the cars were not full, so it is safe to say that 10,000 trains were run in the three days. There are four elevated roads in this town. If the trains had been evenly divided, 2,500 would have been run on each road—an average of 833 for each of 
 Tv vs, %vork satisfactorily, w hile II, ►i►cd itnoliwi way it will work perfectly. Ile may have discovered that a certain oil will answer the purpose, and that no other of the commonly employed lubricants can be depended upon at all. His directions specify the proper meth-od of piping and the proper lubricant, and his deep disgust may be imagined, when, on receiving a complaint of the machine, he finds upon investigation that it has been given treatment which he has demonstrated by trial, time over and again, will invari-ably make the machine work unsatisfactorily —treatment which it was the especial object of his directions to avoid. A I l this, notwith-standing the apparently self-evident fact that any manufacturer of machinery in his right senses would much rather he able to furnish a machine which could not be tis«I improperly, which could be piped in any convenient way, or supplied with any con-venient lubricant, and which would require no directions whatever. In many cases the failure to follow direc-dors may be attributed to mere carelessness —failure to read them, and the supposition that there is nothing mysterious about the machine, nor anything which requires differ-ent treatment from other machinery. In other cases, however, we think the trouble may perhaps be traced to a failure by the manu-facturer to study human nature a little. A friend of ours manufactures a transmission device which is simple in construction, though a little out of the usual line of nut,- chinery used for such purposes. It is in-tended, and under proper conditions does run for months without any attention what-ever, being self-lubricating after the oil res-ervoirs are filled. For some reason which be does not himself entirely understand, there is only one class of oils which will do at all as a lubricant for this machine, experience hav-ing demonstrated over and over that no other known oils will answer. In the directions which accompany the machine it is specified that a certain oil must be used, but in many cases this is disregarded, invariably with bad results. In this case the machines are usual-ly in charge of men who are well acquainted with machinery generally and its manage-ment. Such a man receiving the machine, and perceiving that the directions require the use of a certain oil and no other, is very apt 
liniitilm caliber rillv nifty nictili I1. m1(.1► in ad-vance, instead the contrary. liecent ex-periments seem to prove that it has greater range. 
Cast-iron. 
During the last ten or fifteen years manu-facturers have been learning that cast-iron is cheap, and that it has a value beyond its cost in machine construction. A ton of cast-iron costs, perhaps $16, and it may make, if judiciously used, a machine better by many times its value. This thought comes up from a recent observation of a steam engine that was running what engineers would call under, or left-handed. The frame vibrated, vertically, in a manner that suggested dissolu-I ion. A good deal less than $16 worth of cast-iron would have prevented the trouble, 11 lid paid for itself twice a year in reducing the (Oct of repairs. III to rary Notes. 

TI I I,: EN(d NEERS' EPITOME. A Collection of Figures reacts and Formulas for Engineers, by an Engineer of Thirty Years' Experience. By N. J. Smith, Hartford, Conn. The Mason Regulator Company, of Bos-ton, Mass., has published a series of very useful books for engineers, of which this is t he third one. Of course, this one treats on subjects not found in the other publication of the series. The book is intended for en-gineers whose daily practical duties pre-vented them from giving much attention to the theoretical part of the business, and to place in their hands, in a very convenient form, rules, facts and data of great practical value, and which can readily be applied to solutions of problems which may at any day arise in their business. The first six pages are devoted to decimal fractions, showing how to read and write them, and gives rules for their addition, subtraction, multiplication and division, with examples fully worked out. After this, powers and roots are taken up, followed by rules, facts and data relating to the properties of steam; temperature and vacuum; volume, weight and velocity of steam; boilers; tests for moisture in calorimeter; chimneys; horse-power of engines; thrust on propeller; salt water feed and jet condensers; proportions 
 

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