AMERICAN MACHINIST 
DECEMBER 17, 1887 
and that, after the completion of the job, which consisted in roughing the four sides of the 100 pieces. The periphery speed of the cutter was 26 feet per minute and the feed 3 inches per minute ; time consumed, 44 hours, 39 minutes. Two milling ma-chines were used—one for roughing and one for finishing cuts. The cutters required grinding at the end of the job, and so were chargeable to it ; the time re-quired to grind them was 22 minutes. The wages of boy running the machine was 9 cents per hour. The total cost for finishing the 100 pieces on the milling machine was as follows: 44 hours, 39 minutes, at 4:1- cents each, per hour - $3.99 Sharpening cutters, 22 minutes, at 30 cents per hour   .11 Shop expenses at 35 per cent. of labor  1.39 --- Total cost $5.49 The cost of the same number of pieces finished on the planer was as follows : Planers used were two 16 inches square by 3 feet ; platen running 24 feet per minute cutting speed ; return 2 to 1 ; the feed was as coarse as could be used on the roughing cut—that is, about 22 per inch. Time con-sumed on each planer, 25 hours, 46 min-utes ; wages of man running the planer was 25 cents per hour. The total cost for fin-ishing the 100 pieces on the planer was as follows : 24 hours, 35 minutes each machine, at 
25 cents per hour  $6.03 Grinding and setting tool 19 times, 1 hour, 21 minutes -0   .33 Shop expenses, 35 per cent.   2.22 Total cost  $8.58 
Balance in favor of milling machine.. 3.09 This, you will bear in mind, is showing the planer to its best, and the milling ma-chine to its worst advantage. Where the . milling machine makes the best showing is in irregular work, which, in the planer, re-quires the constant attendance of the work-man—such as planing close to shoulders, cutting bevels and T slots, and jobs of a similar nature. The advantage of the milling machine is then seen, as the cost for attendance is, often, not one-tenth, owing to the fact that a much cheaper workman can run several machines. The cost of tools in each case Company's works, where I now have charge. Since February 15th of this year up to the present writing—Sept. 14th—there has been finished by one set of cutters, about 15,000 sewing machine beds, the cut being about 6 inches long. These cutters have been ground but five times and sho w but very little reduction in size. Common sense teaches that a continuous rotary cutting motion will produce more work than a reciprocating or intermittent one. If in-ventors would turn their attention to the further development of the milling machine, for general machine work, instead of the quick return of planers, they would benefit 
MILLEL .,.LL OVER 12 CUTS 

Front Elevation 

Pig. 6 
themselves and be doing the mechanical world better service. Some of our large machine and tool builders are using the milling machine to their great advantage. The following may be mentioned, who, to my knowledge are using regular and spec-ially designed milling machines to their profit. Brown & Sharpe Manufacturing Co., The Pratt & Whitney Co., The Baldwin Lo-comotive Works, The Straight Line Engine Works,and others. In conversation with one of the members of the society, he mentioned a milling ma-chine shown to him in Scotland, having a face mill or cutter 8 feet in diameter. This machine was used to face off the ends of beams, sheets, and such work. In the construction of machine tools it is possible to mill every part of an engine lathe, a great part with common straight cutters and the balance with special ones. Modern cutter grinding machines, with their attachments, have made it possible to keep cutters sharp and in perfect shape, so that the old and expensive methods of grind-ing by hand, or annealing and working over, need not be resorted to, and modern ideas of 

machinery and tools as are now finished on the planer. In the shops at Flushing, Long Island, with which I was formerly connected, mill-ing machines and special milling fixtures were adapted for nearly every part of the 14-inch swing engine lathe. The only part of this lathe not milled was the bed and a small part of the carriage, and this was under consideration when the partnership was dissolved. As to the cost of milling some of the work, without going into de-tails, we will take the matter of the feed apron, on which there were taken 12 cuts, it being finished all over, being shaped as in Fig. 6. The entire cost of finishing this apron, 16 inches in length and 7 inches wide, was but 7 cents, with the extra ad-vantage of each and every piece being an exact duplicate. Should there be any tool builders present, they can tell the cost of planing the apron shown. A man employed in , the shop offered to finish. 6 feet 14 inch lathe beds for 60 cents each, if I would build for him a milling ma-chine such as had been sketched out. We were at that time paying $3.00 each for planing them. I have been informed that the Pratt & Whitney Co. are considering the feasibility of constructing a milling machine for this purpose. Should they do so, it would be safe to guarantee its practicability. The Putman Machine Co., of Fitchburg, Mass., have, acting upon my advice, made a mill-ing fixture for an 84 inch square planer, for facing up the ends of planer and lathe beds when it is necessary to join them together. This arrangement works perfectly, the ends being milled off before the bed is removed from the planer platen. When bolted to-immense milling machine which they are constructing for their own use. The advantages of the milling machine over the planer are many, among which are the follo wing : Exact duplication of work ; rapidity of production—the cutting being continuous ; cost of production, as several machines can be operated by one workman, and he not a skilled mechanic ; and cost of tools for producing a given amount of work. It is not possible in a short paper to show more than a few of the advantages, but if an interest is awakened in the possibilities of the milling machine, in cheapening the cost of machine work of all descriptions, the object of this paper will be accom-plished. Dean Brothers' Duplex Pump. The duplex pump herewith shown is the recent pattern brought out by Dean Bros., of Indianapolis, Ind. The castings are heavy, and the frame made in straight lines to pre-vent springing. The levers are wrought-iron forgings and the links are of brass. The plungers of water cylinder work through packing rings of brass. Access to the pump valves is obtained through hand holes of large size.

 Shop Notes. 
the shops of E. E. Garvin & Co., in this city, they are quite busy, and are build-ing a good many of their improved screw machines and milling machines. They also have the contract for building the Ham-mond typewriter, upon which they keep quite a number of hands employed. They have in use one of their tapping gether the two pieces are as near a true machines, which is proving itself to be very useful. In general appearance it resembles an ordinary drill press, and instead of tap-ping holes by hand, the parts of machines in which holes are to be tapped are placed upon the table of this machine and tapped by power. By this means better results are secured in the points of uniformity of sizes, square-ness and economy. They are at present building, for a Western manufacturing estab-lishment, a gang drill, to be used for drilling holes in iron pipes, which has some novel features. It has two sets or rows of spindles, one 
plane as it is possible to make such work, while the time consumed was less than it would take to remove the bed and place it crosswise on the planer platen. In several tool-building shops, fixtures are used for finishing the ends of lathe beds, they being bolted to the bed and run by a roundabout belt and having automatic fend. The cost for this work is but little more than the cost of attaching the fixture to the bed and removing it after the work is done. There is hardly any limit to the devices for milling fixtures. Large shafts can be spliced when in position ; key-ways cut 

bar; if this litrained in foc

This, you will bear in mind, is showing the planer to its best, and the milling ma-chine to its worst advantage. Where the milling machine makes the best showing is in irregular work, which, in the planer, re-quires the constant attendance of the work-man—such as planing close to shoulders, cutting bevels and T slots, and jobs of a similar nature. The advantage of the milling machine is then seen, as the cost for attendance is, often, not one-tenth, owing to the fact that a much cheaper workman can run several machines. The cost of tools in each case was as follows : Milling cutters, first cost, $2.10 each. . $4.20 Grinding once, 22 minutes  .11 
Total cost $4.31 Planer tools, first cost, 42 cents .  $ .84 Re-dressing by smith, once  .16 Grinding and setting roughing tools 19 times, 1 hour, 21 minutes  .33 Grinding and setting finishing tool 6 times    .10 
Total cost $1.43 Expense of keeping tools in order on milling machine  $0.11 And for planer   .59 Balance in favor of milling machine  .48 This does not include the time of work-man's loafing in the smith shop, this trouble being entirely done away with in the milling cutter. The milling tools after this trial showed no perceptible wear, or difference in size, and it is safe to say that they would finish, fifty such lots of 100 pieces. The cost for tools in that case would be about as follows : Milling machines, first cost  $4.20 Grinding 50 times at 1.1 cents  5.50 
Total cost 9  70 Planer tools, first cost   $ .84 Re dressing roughing tools 50 times at 16 cents  8.00 Grinding and setting 950 times at 1 73-100 cents    16.43 Finishing tool 10 times at 16 cents  1.60 Grinding 300 times at 1 73-100  5.19 
Total cost.   $32.06 Balance in favor of milling tools. ...$22.36 This calculation on the life of milling cutters is based on what has actually been dome in the American Sewing Machine 
cutters and the balance with special ones. Modern cutter grinding machines, with their attachments, have made it possible to keep cutters sharp and in perfect shape, so that the old and expensive methods of grind-ing by hand, or annealing and working over, need not be resorted to, and modern ideas of plane as it is possible to make such work, while the time consumed was less than it would take to remove the bed and place it crosswise on the planer platen. In several tool-building shops, fixtures are used for finishing the ends of lathe beds, they being bolted to the bed and run by a roundabout belt and having automatic feed. The cost for this work is but little more than the cost of attaching the fixture to the bed and removing it after the work is done. There is hardly any limit to the devices for milling fixtures. Large shafts can be spliced when in position key-ways cut in large fly wheels and in locomotive con-struction and repairs, an immense amount of money could be saved in this way. A large special milling machine has just been finished for use in the Straight Line Engine shops, at Syracuse, N. Y. In a communication received from the presi-dent of the company a short time since, he 

DUPLEX 
the sizes of cutters necessary to do work make their first cost much less. A cutter of 2 inches to 21 inches is now used where formerly it was thought necessary to use one of from 4 to 6 inches diameter. The field of regular and special milling machines for small work being pretty well worked over, what is wanted is more spec-ial machines and fixtures, built for and adapted to the finishing of parts of such PUMP. 
mentioned the fact that the machine was just completed, and he was at that time en-gaged in milling out the T slots for bolt ways in the platen, which was being accom-plished at the rate of two inches per minute A few words from him in relation to its merits, as compared with the planer, would, no doubt, be very interesting, and also the same from the president of the Ferracute Machine Co., of Bridgeton, N. J., on an useful. In general appearance it resembles an ordinary drill press, and instead of tap-ping holes by hand, the parts of machines in which holes are to be tapped are placed upon the table of this machine and tapped by power. By this means better results are securedl in the points of uniformity of sizes, square-ness and economy. They are at present building, for a Western manufacturing estab-lishment, a gang drill, to be used for drilling holes in iron pipes, which has some novel features. It has two sets or rows of spindles, one set being vertical and the other horizontal. The spindles are adjustable as to distance from each other, and are fed automatically, both sets operating at the same time. This firm are introducing in their shops milling operations, to take the place of planing, finding it advantageous to do so, even where the milling requires more time than would be required to plane the piece. This is on account of the decreased cost of the labor required and the greater uniformity se-cured. 

Fair of the American Institute. 
Among the exhibits at the Fair of- the-American Institute, few are of more interest to mechanics than the process of electric welding which is on exhibition there. By this process, which is the invention of Prof. Elihu Thomson, of Lynn, Mass., met-al§ which it has not been found practicable to weld by heating in an ordinary fire, are united readily. Among these we mention cast-iron, brass, copper, zinc and German silver. It is also made possible to weld metals unlike in their nature, such as iron and brass, or iron and German silver. The process seems best adapted to cases where the articles to be welded are manu-factured in large numbers, so that the appa-ratus may be continuously used without change for a large amount of work. The electrical current required must be adapted to the purpose, its volume being regulated to suit the nature of the welding 10 be done. The ends of the pieces to be welded are filed and suitably shaped, and are then clamped to the machine, the ends brought together by a screw motion, a flux applied, 

the fact that they were of a small mass, and partook readily of the same tem-perature as the air. Prof. S. W. Robinson gave a description of the method employed in measuring a base-line in the ordinary way. A clearing is pre-pared and graded as carefully as a railway bed, and the apparatus employed is very bulky. He also mentioned another methed that he had employed some years ago, of measuring with a steel piano wire having circular pieces fastened on it at the measuring points. Around the circular pieces V-shaped grooves were cut. In using the wire the circular pieces were held against ordinary surveying pins. If the operator happened to pull too hard on the wire while it was be-ing held against the pin, the form of the groove was such that the circular piece would slip by the pin without tending to displace it. This method was recommended only where moderate accuracy is required. 

Launch of the Cunard Twin-screw

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pg-3 AMERICAN MACHINIST  Oct-17-1887   AMERICAN MACHINIST 
and the current turned on. The ends immediately begin to heat, and as they soften are crowded together by the Acrew motion before alluded to. The welds are made very fast, and if de-sired, the work may be hammered while the welding is going on. It is well understood that as a metal be-comes heated, its conducting power is de-creased, which, of course, means that its resistance is increased, and in that part of a piece of metal in which the resistance is greatest, the most heat will be developed. For this reason, the work may at any stage of the process be removed tempo-rarily, and when replaced, the further heat-ing will be confined to the part already heated. It is also because of this principle that remarkably even heating is secured, because the parts which are the coolest become the path for the greatest current, until the tem-perature is equalized. Of course the process is a comparatively cleanly one, and we think will prove valu-able in many lines of manufactures. Practical Drawing. 
By J. G. A. MEYER. FIFTY-FOURTH PAPER. Problem 51. To FIND THE HORIZONTAL • PROJECTION OF A RIGHT CYLINDER, ITS VERTICAL PROJECTION BEING GIVEN, THE AXIS OF THE CYLINDER IS PARALLEL TO THE VERTICAL, AND OBLIQUE TO THE HORIZONTAL PLANE OF PROJECTION. The method for finding the projections of a cylinder when its axis is perpendicular to the horizontal plane of projection is given in Art. 301 ; and the same method for finding the vertical projection is also used for finding the vertical projection of a cylinder when its axis is parallel to the vertical plane of projection, and oblique to the horizontal plane. Now it often happens that cylindrical bodies, when shown in connection with other bodies, must be shown in an oblique position ; cases of this kind frequently occur in making general plans of machinery; it is therefore necessary to know how to lInd the projection, as shown in Fig. 267, of 
points c3 and d3 equal to that between the points c, and d2; j 13 equal to j2 12 and 13 k3 equal to la 2. With the aid of one of the irregular curves shown in Figs. 128 and 129, join the points ms, fs, h3, c3, jg, 13, 113 etc. The curve so formed will be the hor-izontal projection of the upper base of the cylinder. In a manner precisely similar to the foregoing, the curve 03, d7, c7, p3 is found, which is the horizontal projection of the lower base. It may be remarked that the distance between e7 is equal to that between f2, e2; h7, g7 equal to h2, g2, and so on; otherwise the construction for finding the horizontal projection of the lower base is plainly shown. Join the points c3 and e7; also the points d3 d7 by straight lines, which will complete the horizontal projec-tion os, d7, d3 7-63, C39 e7 of the cylinders. 
The straight lines d3 d7 and c3 c7 will be -Fig • 267 tangent to the curves, and their lengths lim-ited by the points of tangency if the curves have been correctly and accurately drawn. The portion d7, 07, p3 of the lower base must be dotted, because it is hidden. 
points, m, f, etc., as we have done, this problem, which at first sight may have ap-peared to be a difficult one, is reduced to a very simple one, for now we have only to find the horizontal projection of these points, then join these by curved lines, which will represent the boundary lines of the bases in the horizontal projection of the cylinder. Before we can find the horizontal projec-tions of these points, we must know the relative posit ions of the same to some known plane or given line. Thus for in-stance : We may find the distances of the points m, f, h, etc., from the vertical plane of projection, or we may find the distances of these points from a diameter drawn parallel to the vertical plane of projection. We will adopt the latter method, because, by doing so, the construction will be simpler and re-quire less labor. Let us revolve the project-ing plane, which contains the upper base, around its trace m n, until it stands parallel to the vertical plane of projection ; and in this position of the plane the upper base will be represented by the circle c2 d2 m2 n2; in fact, by turning the projecting plane with the base around the trace m 71, we bring the base into a position in which its true bound-ing line-which in this case is a circle-can be seen. In turning this plane around the trace m n, the paths of the points m, f, h, c, etc., will be represented by lines drawn through these points perpendicular to the line m n (Art. 322), and since these points are also the extremities of the elements which are perpendicular to the same line m n, it follows that the lines m m2, f f2, c c2, etc., which represent the paths of the points, are continuations of the lines which repre-sent the elements, and therefore the center c., from which the circle has been described, must lie in the line c c2; and the positions of the points f, h, c, after the projecting plane has been revolved, must be found in the 
12 

the line o3n3 parallel to A B is drawn; the points m3 n3, in which the verticals through m and n cut the line 03 763, will be the ex-tremities of the• diameter in the horizontal projections ; consequently the lines m3 ns, 9722 n2 and m n will all represent one and the same diameter. We notice that the line f f2 cuts the diameter m2 n2 in the point f4, and the circumference in two points, namely, f2 and eg. We have already seen that the point f represents the point f2; it must now be added that the point f also represents the points A and e2, because the points f2, f4, e2 lie in the same plane and in one straight line, and when this plane is turned around the line m n until it stands perpendicular to the vertical plane of projection, the line f f2 will also stand perpendicular to the same plane of projection, and the three points, e2, f2, f4, will be represented by the point f. For similar reasons, the point h will represent the three points g2 h2 h., and the same remarks apply to the points e, j, 1. In Article 227 we see that the horizontal and vertical projection of a point must lie in one straight line drawn perpen-dicular to the ground line A B, and there-fore the horizontal projections of the three points represented in the vertical projection by the point f must lie in the vertical line drawn through f, and since m3 768 is the horizontal projection of a diameter parallel to the vertical plane of projection, it follows that the point A, in which the vertical through f cuts m3 n3 must be the horizontal projection of one of the points represented by f, namely A. The other two points, e2 and f2, represented by the same point f, must, also lie in the same vertical, and their dis-tances from the diameter m3 ns must be equal to the distances between the points e2, f2 and the diameter m2 n2. Therefore from the point A as a center, and with a radius equal to f4 f2 or A e2 (both these lines are equal in length), we describe small arcs, cutting the vertical in the points f3 and es, which are two points in the boundary of the horizontal projection of the upper base. Similar reasoning is applicable to the method of finding the points h3, j3, c3, etc., and also to the method of finding the hori-zontal projection of the lower base. We join the points c3 and c7 by a straight line, because these points are the extremi-ties of the element to which the projecting __1_____ ,. ,,+ rip 1, v.. ‘,7 , 1 .7 

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pg-4   this is a test------ In our issue of May 21st we published cuts showing sectional and detailed views of this engine, since which time the new form, herewith shown, has been brought out. It has two vertical cylinders, placed side by side, the principle of its action being practically the same as the single cylinder engine, which was fully explained in our former issue spoken of above. In this engine the wrist pins are placed 180° apart, so that, notwithstanding the fact that the engine is single acting, there is yet a constant action upon the crank shaft. The wrist pins are placed at an angle with the crank shaft, and thus a spiral motion is imparted to the piston, by means of which the steam and exhaust ports are opened and closed. In this way the usual valves and eccen-trics and their attendant mechanisms are dispensed with, and the number of parts composing the engine very much reduced. This of course reduces the friction of the engine, since no slide valve is to be moved, and there are no stuffing boxes. The makers state that they so arrange the various parts as to secure the best and most economical distribution of steam, that no wear can take place which affects this distribution, and that the engine cannot be tampered with so as to affect it. Most mechanics are familiar with the fact that only a comparatively very small force is required to impart a rotary motion to a cylindrical body which is already in motion endwise, and it is, in part, owing to this circumstance that in this engine the power expended in steam distribution is re-duced to a very small amount. The reversing mechanism consists simply of a three-way cock by which steam is changed from the steam port to the exhaust port, and vice versa, which, it is claimed, makes it an especially desirable engine to use for hoisting purposes, or for launches or small boats where frequent reversals are necessary, and yet where it is especially desirable to secure simplicity and the least possible necessity for attendance. The exhaust takes place at the end of the downward stroke and carries with it all water of condensation. 
 

Pig. al RESISTANCE OF CYLINDERS TO BURSTING. 

A new use for cement has been found in England in the making of telegraph poles. The poles consist of an iron shell filled up with the cement or concrete, which in-closes a core of wire netting which is car-ried up the interior. They are claimed to be much lighter than those of cast iron and practically indestructible. 
The Resistance of Cylinders to Bursting Pressure. 
BY W. H. BOOTH. 
It might be thought almost unnecessary to say anything upon the method of com-puting the bursting strength of a cylindrical pipe, boiler or other metal, but a most re-markable example of ignorance upon the subject has just been placed on record in connection with the recent disastrous ex-plosion of a copper, steam pipe on board the English steamer Elbe. That eminent expert, David Kirkaldy, of world-wide fame and reputation in his own special line of business, has shown, before a committee appointed to inquire into the explosion and to trace its cause, that he is utterly at sea 

upon this important point, and however re-liable he may be as an authority upon the behavior of iron and other materials under direct stress, he appears to know nothing of how to calculate mixed stresses. Before the committee Mr. Kirkaldy ex-plained his method of calculation, which was to multiply the circumference of the cylinder by the pressure of steam acting within it. The product would be the stress on a strip of metal 1" x t, where t is the thickness of the metal in the pipe. Now, the circumference of a pipe is just about 61 times its semi-diameter, and the really cor-rect way of figuring out the stress is to multiply the semi-diameter of the pipe by the pressure and the product is the stress on a strip of metal 1" x t. 

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Let us figure out by both methods the case of a 9" pipe, 1" thick, and subject to an internal pressure of 100 pounds per square inch. By Kirkaldy's method we have the circumference =9" x 3.1416 = 284", and 281 x 100 lbs. =2,825 lbs. on a strip of the pipe 1" x 41". Hence 2,825 x 4 =11,300 lbs., as the stress per square inch on the metal of the pipe. Now for the correct method : The semi-diameter is 471", and 41 x 100.,lbs. =450 lbs. on a strip of metal 1" x 1" or 1,800 lbs. per square inch of the material. If the ultimate strength of the material be sup-posed as 18,000 lbs. per square inch, our pipe would have a marginal factor of 10, which is sufficient ; but by the Kirkaldian method of calculation an attempted factor of 10 would really be over 60, and result in frightful extravagance. In fact, Mr. Kirkal-dy's method would do very well by which to dimension pipes, if the working stress were taken fully up to the ultimate strength of the material, for we should still have a factor of 61. There are doubtless others who are under misconception on this very subject, and we will try to make it clear. In our Fig. 1 the cross-section of a pipe may be supposed. If this is burst it may tear longitudinally at any point, and we may suppose, correctly and logically, that it will as probably tear at one of the two places marked as elsewhere. If equally strong at any two places, it would tear at both of them ; but some one part is certain to be the weakest, and there rupture takes place. Suppose now, in Fig. 2, that a flat central wall is built in the pipe. We may still suppose fracture would occur at the point marked. Now, in each of these semi-cylinders the pressure is everywhere, of course, normal to the surface ; for if not, motion of the contained steam would take place and it is this fact that leads the circumferential men into their error ; for they say that the half circumference is more than 50 per cent. longer than the diameter, and thus carries more pressure. They forget that if the pipe ruptures at, say a, the arrows repre-senting the steam pressure are not all square, or nearly square, to the line of rupture; arrow b, for example, having made no effort in making a tear at a, though fully effective limn section r_ fnr 
• 

The reversing mechanism consists simply of a three-way cock by which steam is changed from the steam port to the exhaust port, and vice versa, which, it is claimed, makes it an especially desirable engine to use for hoisting purposes, or for launches or small boats where frequent reversals are necessary, and yet where it is especially desirable to secure simplicity and the least possible necessity for attendance. The exhaust takes place at the end of the downward stroke and carries with it all water of condensation. All other points were covered by our former description, and need not be re-peated here. The engine is made by the Castle Engine W9rks, Indianapolis, Ind. 
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of business, has shown, Detore a committee appointed to inquire into the explosion and to trace its cause, that he is utterly at sea 
Crystallization by Repeated Heatings. Thomas Edington & Sons, of the Phoenix Iron Works, Glasgow, write to Engineering as follows : SIR : We have observed the correspond-ence on this subject in your journal, and we think our experience may prove interest-ing. In the manufacture of cast-iron pipes of small diameter, we use as core bars iron tubes made from strips of good quality ; these bars are exposed to a temperature of between 600° and 700° Fahr. in the drying stoves, and again to a high temperature when the metal is poured into the mould. The result of the repeated heating and cool-ing is an alteration in a very short time of the structure of the iron from fibrous to crystalline. The stoves for drying the:cores are heated with gas from a Wilson:pro-ducer, so that in this case the change of structure can scarcely result from the pres-ence of finely divided carbon. We find,that the wrought-iron in the spindles of core bars for large pipes is affected in the same way. Again we find that the chains, used for suspending pipes in the dipping pans, lose their fibrous structure in a comparatively short time, although the temperature of the coating mixture never exceeds 350° Fahr. Of course, while exposed to this tempera-ture, the chains are always in a state of ten-sion, which will vary according to the weight of the pipes. --This is a test of the dill

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IMPROVED CASTLE ENGINE. 
to the surface ; for if not, motion of the contained steam would take place and it is this fact that leads the circumferential men into their error ; for they say that the half circumference is more than 50 per cent. longer than the diameter, and thus carries more pressure. They forget that if the pipe ruptures at, say a, the arrows repre-senting the steam pressure are not all square, or nearly square, to the line of rupture; arrow b, for example, having made no effort in making a tear at a, though fully effective upon section c, for example. Thus it is that the circumferential, or rather the radial pressure lines, require reduction, as they do not all act with their full energy at any one section of the pipe. How can we prove our statement by actual experiment ? Very easily. Cut away all that half of the cylinder marked E, and fill the remainder with steam or water at pressure, and then fix the semi-cylinder to end pivots upon a truck on wheels. Now, if the pressure on the semi-circum-ference is greater than the pressure on the flat side, what would be the result ? Why the wheeled truck would move in the di-rection of the round side. So, we should obtain motive power for nothing, but the expense of filling a few half cylinders with water under pressure. What a giant dis-covery have we here ? Ile whole world would be revolutionized; but, unfortunately for perpetual motion, the truck would re-main at rest, and this would prove that at the points a and b the stress is simply that due to multiplying the diameter by the pressure, and dividing the result equally between the thickness of metal at a and b, or any other diametral section. We may express this in the shape of a rule, as fol-lows : ' To find the stress on the material of a pipe, multiply the diameter in inches by the pressure in pounds per square inch, and divide by twice the thickness of the pipe. The result is the stress per square inch of pipe. To find the bursting strength, divide the above result into the tensile strength of the material of the pipe, and the result multi-plied by the pressure above used will be the bursting pressure. As an example, take the nine inch pipe quoted above, and 100 pounds pressure. 
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purpose.

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pg-14 Ads     AMERICAN MACHINIST   Dec 17, 1887 

cam to contend with I have not, as I use flat plates; the cam curves developed upon them, and fastened to the slide C. As the worm controls the movement of both the spindle and slide, the speed is the same in both. The slide A can be fastened to any milling machine platen; a pin with a roll is driven into it, and passes through the cross-slide to the former, which drives the spindle head B B forward or back as the spindle rotates. The length of the formers is the circumfer-ence of the worm gear on the pitch line plus what is necessary for fastening. In using this. fixture you would have to keep this in mind in timing cams, as the same length of former does for all sized cams. By hinging head B, and removing slide C, and replacing by angle plate D with roll on, and placing former on spindle extension, you can cut any shape or kind of cam with the same fixt-ure. This may be an old idea, but was new with me. C. F. SMITH. 
Flies and Drawing Ink—Learning—American Boasting. Editor American Machinist : It has been my experience to find flies with a very decided penchant for Higgins drawing inks, and have found muriatic acid a good antidote to drive them back to their proper sphere. I tried hartshorn, but don't know whether the flies became accustomed to the combination or evaporation took place. I take exception to your rubbing fresh ink every morning and noon, because it takes time; time is money, and, furthermore, a draftsman cannot " think " and rub ink at the same time. W. goes at the kernel of the nut in good shape in his " Practical Talk to the Boys." The apprenticeship question is one that demagogue workmen and fool employers always try to cDmbat and surround with mystery. My advice to the young man de-termined to succeed as a mechanic, is to go on and up. Don't change from your present place for the sake of more pay, but if you are not learning now, change to the shop where you will learn, and opportunities be given for you to learn. I would just like to say one thing on the " American Boasting " discussion Mr. 
bors. Now over here in the old country I believe I should be safe in saying that nine persons out of ten, if asked the question, would say: "Americans! Why, of course, they are all boast" ; they would probably say so, whether they knew anything about Ameri-cans or not, as it is generally accepted as an axiom on this side the water. Where there is smoke one is justified in suspecting fire. Personally, however, I believe that what we so generally put down as brag on the part of our American cousins is more a matter of 
than we find their prototypes over here to be.. There are few civilized countries who do not possess some, perhaps many reasons for national pride, and which may be far from the region of boast ; but in this matter it is for we machini'ts and engineers to con-fine ourselves to our profession. Myself, as an engineer, I ignore the demarkation of territory; as an engineer I claim the world as my country, and all engineers as my countrymen. feel nearer akin to that brown-skinned fellow-creature and fellow-machinist who made 

pleasure, not the boast, is ours, we machinist's and engineers. As .hinists we are working in differ count la,' different conditio may learn from each other and adm. other's good work. Our endeavor she by our works to show the best that can done under the conditions we are placed in. It is our destiny, more than that of any other profession, to alter the face of the world, to open up and utilize her resources for the benefit of mankind. You of us in America are showing us how to make machine tools, Corliss engines, etc., and how to illustrate them and print their description, and you have shown us the way in systematic production, which is the best thing, perhaps, you ever have shown us. We others in the rest of the world are also doing something; let us waste no time in boasting of what we have done, but show the world how much better we can do. FRANK LESTER, M. Inst., M. E. England. 

New MILLING MACHINE. 
The accompanying illustrations show a new milling machine, and a patented circular milling attachment recently put on the mar-ket by the States Machine Co., of Hartford, Conn. Fig. 1 shows the milling machine, and, as will be seen, its construction possesses stabil-ity, compactness and simplicity ; it also em-braces some new and advantageous features. The frame, including the arm supports, is one solid casting, and designed to resist with safety all strains to which it may be sub-jected. The cylindrical arm is placed 12 inches above the spindle center ; for large machines it is 54 inches diameter. Its bear-ing extends throughout the whole width of frame, and the arm has a large range of adjustment. The pendant is loose, and is also adjustable, so that it may be dropped inside of the work, where it cannot be swung in. The back gears lie entirely inside of the frame, and are out of the way. The main spindle is large in proportion it runs in double-tapered steel bushings, hardened and ground to fit, and provided with means for taking up at both ends of the bearings. The end of the main spindle is not only bored out tapered, but it is, throw- 

place for the sake of more pay, but if you are not learning now, change to the shop where you will learn, and opportunities be given for you to learn. I would just like to say one thing on the " American Boasting " discussion Mr. Sweet has not said one word about any other nation's boasters. I have put a Yankee and an English engineer together, and two greater braggarts I never listened to; they had performed wonderful things, but not half so great as they imagined. The Scotch-man does not brag much; he is after pelf. The German is a combination of the Eng-lishman and Yankee in boasting, and excels his English brother in copying and purloin-ing the products of others' brains. But the nervy Frenchman, with his electric waltzing from alpha to omega in mechanics, and back again, searching for ways and means to ac-complish desired results, without ever telling us who he was or where he came from, and his more slow-going, colder blooded brother mechanics from Norway and Sweden have always been my ideals. Being a student of human nature, as well as a mechanic, I have long noted these things, and feel that my friend Sweet is perfectly justified, so far. There is an old and true proverb, thusly, " He that htimbleth himself shall be ex-alted." This has been Professor Sweet's maxim throughout his mechanical life, and unconsciously too, I think. How many of us who stand ready to score and criticise his honesty in " giving the devil his due " can say the proverb fits us ? THE OLD MAN. 
American Boasting. Editor American Machinist : " Spare the rod and spoil the child" is perhaps one of the most practical proverbs in the language; at all events it is so, without doubt, in the opinion of the child. American machinists are favored in hav-ing so judicious a wielder of the rod as they possess in the person of Prof. Sweet. To be brought to task for one's shortcomings is a most salutary exercise, and cannot fail to benefit. As a rule, if you want to know your failings, and have them shown up full size, it is only necessary to apply to one's neigh-

    habit, a national habit, than a real intention to boast. If we get down to the bed rock of the thing, the real intentional boast, I believe we should find as great a proportion, especi-ally of mechanical boasters, in Great Britain as in the United States; at all events, if not boasters, individuals who possess a most gi-gantic opinion of themselves, which amounts to the same thing, and unfortunately we generally find that this class of people base their pretensions on a most quicksandy foundation, and that real merit loves seclu sion. It is to be hoped that those Americans who do boast are more justified in doing so 
the curious ball, or to that African smith who forged those curious chains, or to that American who made that highly-finished automatic screw machine, than I do to my lawyer neighbor next door, and wherever my profession achieves a triumph of ingenu-ity, of skill, of accuracy and finish of work-manship, I share in the pride of it—it may be in my own little works, it may be in India, Japan, Germany, America, I care not where; I do not quarrel as to what particular country belongs the honor of the steam engine, the electric dynamo, or any other mechanical triumph over nature; the honor is ours, the 
frame, and are out of the way.

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