Mr. Diesel's theoretical work has been thoroughly investigated and endorsed by such prominent scientists as Prof. Zeuner, Lord Kelvin, Prof. Schroeter, Prof. Denton, Prof. Thurston, and others.

The motor, however, speaks for itself in the practical results already obtained, as shown by the accompanying table.

These results are the more astonishing when compared with the equivalent in effective work obtained with other motors. For example, the very best steam engines give but little better than 13 per cent. of the total available heat in effective work; and the total efficiency of the gas engine employing the Beaŭ de Rochas cycle, while better than the steam engine, scarcely ever reaches 18 per cent.

The combustion of the fuel in the Diesel motor is practically perfect. The exhaust of one of these engines discharging within a few inches of a wall of white enameled brick left no perceptible stain after a year of steady operation. Careful chemical analysis of the exhaust gases fails to show more than a mere trace of unconsumed fuel.

The engines are now being built by several European firms under the Diesel patents, and several American manufacturers are arranging to take the matter up, at least one American firm having already started their manufacture.

The policy of the owners of this patent is a most generous one. Unlike the Corliss engine when first introduced, the rights of manufacture are not to be the exclusive property of one firm, but the patent rights are evenly distributed, in order to encourage competition and to insure the rapid introduction of the motor.

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THE DIXON CRUCIBLE COMPANY, of Jersey City, N. J., has published a little pamphlet entitled " Helps in Brazing." It treats incidentally of brazing graphite, the application of which to bicycle tubes prevents the adherance of the spelter, and so effects a saving in labor by making unnecessary the filing which is otherwise needful. The pamphlet, however, treats especially of the process of brazing by the dipping method, or "liquid brazing,' as it is called. The brazing crucible is described, together with instruction and caution in regard to its use. Instructions are given how to build and set the necessary furnace, time required for brazing, etc., etc. In regard to the economy of liquid brazing as against the old-time fire brazing, the following is quoted from a well

known bicycle manufacturer: "We have been using the process of liquid brazing all this season, but at first found some difficulty in keeping the spelter at the proper temperature. We built several furnaces before we succeeded in getting one entirely successful. The one we have now in operation enables us to do as much work with one man and a boy as we were able to do before with five to seven men, and the results are much more satisfactory. We figure that we effect a saving of $20 per day, every day we run the new furnace. Besides requiring fewer workmen, we use only about 125 pounds of hard coal in a day's run, which is quite a contrast to the expense we were under with the old gas furnace, when our gas bills amounted to $250 per month. With the new process one man and a boy can turn out seventy-five machines in a run of seven hours." The pamphlet is of interest to all manufacturers and others who do brazing. It is sent free of charge.

JAMES L. ROBERTSON & SONS, 204 Fulton St., New York, inform us that the demand for Eureka packing is still increasing, and that they have recently added to their numerous list of customers many large manufacturing concerns. Their sales for August amounted to over 6 tons, which went to all parts of the globe. The excellent reputation that Eureka packing has gained rests upon its uniformity of quality, and the high grade of materials that are used in its manufacture. The makers are always glad to send samples and trial lots to interested parties, free of charge.

CATALOGUE REVIEWS.

THE ARMSTRONG MANUFACTURING COMPANY, Bridgeport, Conn., issue for 1898 a 54-page catalogue and price list of their well known stocks and dies, and other tools for the use of water, gas, and steam fitters. Size of book, 7" X 5". Particular attention is called to a line of newly designed machines for threading and cutting off pipe. These machines, which are of excellent design, are made in five sizes; the smallest one threads and cuts off pipe from 1 to 3 inches inclusive, while the largest size deals with from 1- to 6-inch pipe. An excellent feature of these machines is that all the driving gears are enclosed in an oil chamber, by which means they are not only thoroughly lubricated but are kept free from dirt and chips.

catalogues, numbered respectively 16A and 16B. The first of these is devoted to their footand hand-power wood-working machinery, and embraces an exceptionally full line of machines specially designed for the use of carpenters, builders, cabinetmakers, patternmakers, etc., such as scroll saws, combination saws, molders, and foot lathes. No. 16B is entirely devoted to foot-power lathes and accessories. The lathes and other foot-power machinery manufactured by this concern are fitted with a patent "walking-motion" foot power, which is claimed to be an improvement on anything heretofore brought out; the levers are so arranged as to give great freedom to the operator, and can be worked with either foot, while standing, or with both feet while sitting. A special feature of the lathes is an end-thrust ball-bearing spindle, whereby the friction during drilling is reduced.

BOOK REVIEWS.

HAND BOOK OF CORLISS STEAM ENGINES. Cloth. Size 74. Seventy Illustrations. By F. W. Shillitto, Jr. Published by The American Industrial Publishing Co., Bridgeport, Conn. Price, $1.00.

This little book is written for the purpose of giving the practical information most needed by the working engineer who must superintend the erection of a Corliss engine, and make correct adjustments of its valves and other working parts. The section on erecting Corliss engines gives excellent general directions for the construction of foundations, which apply equally well to foundations for engines other than the Corliss. The directions for setting up and lining apply particularly to the regulation type of Corliss engine, and are clear and practical. The section on adjusting explains briefly the general features of the Corliss valve and gear, and its relation to the ordinary slide valve. It also points out the principal differences between the various types of Corliss gear in common use, and shows how the setting is modified to suit these different types. The chapter on the use of the indicator in valve setting is, perhaps, a little too brief. Although, as the author states in his preface, there are many excellent treatises on the use of the indicator now to be had, it would have made this book more complete, and added to its value as a practical engi

neer's handbook, if the special application of the indicator to Corliss engine practice had been made more comprehensive. Some of the leading types of Corliss engines now on the market are illustrated and briefly described. The book will be found particularly useful to young engineers who wish to become thoroughly familiar with the Corliss valve gear and its adjustments.

PRACTICAL SHOP TALKS. By Fred H. Colvin. Cloth, size 6" X 34, 144 pages. Published by The Locomotive Engineering Co., 256 Broadway, New York. Price 50 cts.

In this little book, "A collection of letters on shop subjects which show by actual examples some of the existing methods of shop management and practice," Mr. Colvin, whose experience makes him familiar with many methods of shop management and incidentally-mismanagement, writes as one who would say to employer and employee alike, "Why don't you open your eyes and see the many little foolishnesses that exist and thrive in your shop? Why don't you look to it that Mr. Theory and Mr. Practice work together in a friendly manner, and that Mr. Draftsman is respected as he should be and paid as he should be? Why don't you say to Mr. Ignorance whom in your own ignorance you clothed with authority some years ago, 'Get out of this! I have found you out; my foreman must know more than simply "Where things are kept" and "How we always have done it." He must be an energetic, practical man— of varied experience, and of some originality.'" In a delightful conversational style, many amusing dialogues are introduced, in which the author shows that he knows a good deal about machine-shop practice and of human nature too. He depicts the disasters caused by the office interfering with the shop; shows how foolish it is to do a thing in a certain way simply because it always has been done that way; points out the vast importance of shop system, of building machines in lots, of paying good men well and of employing none but good men; and so on. "Practical Shop Talks" originally appeared in "Machinery" as "Notes from Notown' by Ichabod Podunk." Those who then had the pleasure of reading the letters will no doubt be glad to possess them bound in book form.

Answers to Inquiries, No. 266 (c), which read Can Mushet's steel be annealed?" we answered "No." This was an error. We are indebted to B. M. Jones & Co., Boston, for the following information: There is no steel made that cannot be annealed. The following are our directions for treating Mushet's special steel, to make it adapted for milling cutters, taps and dies, reamers, rose bits, countersunk drills, and twist drills: After the steel is forged, heat it up thoroughly to a light yellow (short of burning), and bury it in hot ashes from the smithy fire, or in lime, and cover over with fine ashes or sawdust, so as to exclude the air thoroughly till perfectly cold. The steel will then be annealed for turning, filing, etc., but, if it is found to be hard below the surface, when cut into for working, it may be necessary to anneal again before finishing.

To Harden it Again.-This may be done with the entire piece, or in any one part of the piece, leaving the rest annealed, viz. :

For Hardening Milling Cutters.-Heat up to a bright yellow (short of burning). If the "cutters" are thin, cool in the air, suspended by a wire. If they are thick, they should be cooled quicker by holding them over a strong cold-air blast pipe and kept slowly revolving in the blast till cool.

For Hardening Taps and Dies.-Heat a tap quickly upon the threads (which always catch the heat first) and cover quickly with the cold-air blast; afterwards heat the "square" at the shank of the tap to a good red, so as to harden it sufficiently for use. This same treatment will apply to reamers. For long taps and reamers there is not the trouble of "twisting" that there is in water-hardening steel.

For Hardening Screw Dies.-Heat them quickly on the thread, and cool them in the cold-air blast. This will also indicate the treatment for the hardening of other articles.

Local Hardening.-Take care to cover the parts that are intended to be left annealed with clay, or any "composition," say asbestos, and heat the exposed part, which is intended to be hard, and cool quickly in the cold-air blast. For hot punching and cold punching, the steel should be annealed and hardened at the point. For shear blades for cutting hot iron, the steel should be annealed and hardened on edge. For wearing parts of heavy machinery, the steel should be annealed and hardened.

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(443) In your September issue I note Mr. Thomson's article entitled Greenhouse Heating." I have a conservatory on the northwest side of my house that gets very little sunlight. Would a system such as you describe be suitable for my place, and could the conservatory be used for raising or keeping anything besides green plants during the cold winter months? E. A. R., Baltimore, Md.

ANS.-A hot-water heating system like that described in our September issue is suitable for any

need not necessarily be a "lean-to," and it does not require to be close to the building. You can easily heat a small greenhouse with such a system, even although it is as far as 100 feet from the building in which the boiler is located, provided, of course, that the boiler is a few feet lower than the greenhouse heating coils. It is a pity that your conservatory does not face the south, because then you could have the full value of the sun's rays, and the plants would thrive so much better than they will in a shaded greenhouse. Nearly all ordinary plants can live in your greenhouse during winter, if you furnish proper heat and ventilation, but they will not bloom so well or be so healthy as those that have plenty of sunshine every day.

figure, which has all the dimensions required. The section of the packing may be circular at the bottom, as shown at a, or it may be flat, with rounded corners, as at b; in any case it should be made to fit the recess as neatly as possible. Take a ring of leather of sufficient size to make the packing as shown, using closegrained leather of uniform thickness, and soak it in water until it is perfectly pliable. Press it carefully and evenly into the mold and let it remain for about 12 hours, then take it out and let it dry, after which it may be trimmed, when it will be ready for use.

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(445) (a) In regard to the gas-engine igniter described in HOME STUDY MAGAZINE, March, 1898, Fig. 4, I would like to know if this igniter is as reliable as the other forms described. (b) What should the length of the spark be? (c) Please give the dimensions of the coil; also, the size of wire and number of layers in each of the primary and secondary windings. (d) How can I make the coil waterproof? L. J., Jamestown, N. Y. ANS. (a) The igniter referred to is used on the Priestman oil engine, but the one shown in Fig. 5 in

the article referred to is in more general use by gasengine makers. (b) A 4-inch spark would probably answer your purpose, but a 4-inch spark would be more certain to ignite every time. (c) For a 4-inch spark coil make a core of No. 16 annealed-iron wire. The core should be 4 inches long and inch in diameter. Cover this core with paraffined paper

inch thick, and wind on the primary coil, allowing inch of the core to protrude from each end of the winding. The primary should consist of three layers of No. 16 single cotton-covered magnet wire, and each layer should be shellaced. Cover the primary with paraffined paper inch thick, and wind on 88 ounces of No. 34 single cotton-covered magnet wire, run through paraffin while winding. (d) Immerse the entire coil in paraffin, and box it up, leaving only the terminals and the circuit-breaker outside the box.

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(446) (a) Two engineers were engaged in the discussion of the "lead" of a locomotive engine; A claimed that it was done by the blade of the eccentric, while B maintained that it was done by the eccentric itself; who was right? (b) If the lead is brought about by the eccentric alone, how is it that when you hook up the reverse lever, the lead is increased? (c) When an engine is working steam with dampers closed, will the tubes be affected so as to be likely to leak? An engineer I know claims that an engine working steam under the above conditions creates vacuum. Is this so? (d) How would you set a slip eccentric of a Vauclain compound? Has this engine an intercepting valve? (c) Our master mechanic relates an instance where an engineer on a "freight" was to meet a "passenger' half way on a 9-mile down grade, and remembered it when but two miles from the meeting place. When he attempted to apply the brakes, he found the pump was stopped; knowing it was useless to call the brakeman's attention, he worked both injectors, filled the boiler, worked engine in back motion and thereby came to time. Is any such thing possible?

R. F., New Orleans, La.

ANS.-(a) B was right. (b) It is quite true that altering the length of the eccentric blade or rod will increase the lead, but only at one end of the stroke; it will decrease it at the other. Moving the eccentric around on the axle gives lead at both ends, or

fore and back eccentric rod pins, and 17 the link are (the center line of the curved slot in which the link block slides). p is the center of the link block (and, therefore, of the rocker pin when there is one), and as this governs the position of the valve, the vertical line pv shows the position of the steam edge r of the valve when the crank is on the back center, the lead being as shown. Now lift the link into midgear. The new positions of f, b, l, and p are f. b', l'. and p'. The vertical line p' determines the new position of the steam edge of the valve. Thus, the lead has increased from se to sv'. This increase is, on the average, about inch; that is, an engine having -inch lead in full gear will probably have about inch in mid-gear. The actual variation depends on the length of eccentric rods, distance between eccentric pins in the link, etc. If the rods were crossed, that is, if F were connected to b and B to f, the lead would decrease as the link was lifted into mid-gear. It is the practice now to adjust the lead for the "running position" (this is generally from 25% to 30% in passenger engines under normal conditions). A full gear lead of inch would give more lead in this position than is considered desirable: inch is the amount usually chosen. To obtain not more than this amount will necessitate the valve being set from

inch to inch "blind" in full gear. If the engine has rockers (as all American locomotives have) the crankpin will be on front center at P, with the eccentrics in their present position, each being 90° angle of advance behind its respective crank, instead of 90° angle of advance ahead of it, as in sketch. This is true, roughly speaking; as a matter of detail, it would only be the case if the center line of motion coincided with the axis of cylinder, a state of affairs very seldom occurring in this country. (c) There is always a certain amount of vacuum produced in the smokebox, owing to the exhaust. To fill the space left vacant by the withdrawal of the air, induced by the blast, other air finds its way in, if possible. If the smokebox door is perfectly air tight, as it should be, air to supply this loss can only come in from the firebox, either through the dampers or else through the firehole door. The less the door is kept open the

decreases it if moved around in the other direction. In the accompanying sketch, it will be seen how the lead increases toward mid-gear. To simplify matters, the rocker has been omitted and also the valve rod and stem, making the valve appear to be directly over the link. P shows the crankpin on the back center, F and B representing the centers of the fore and back eccentrics, respectively. The dark outline full represents the link (at least enough of it to answer our purpose), f and b being the centers of

b

better, as this is a fruitful cause of leaky tubes. If the door and dampers are shut tight, the vacuum in the smokebox will become more perfect. The amount of vacuum actually obtained varies with the boiler pressure, cut-off, amount of throttling. and the size of blast nozzle and chimney. As regards the tubes leaking, the most frequent cause is, as before remarked, the opening of the firedoor, thus letting cold air strike the back tube-plate. This is particularly the case when no deflector or baffle plate

is used inside the firehole opening. Another injurious practice is to turn the feed on when drifting. If this is necessary, the blower should be started, so as to have a good draft of flame through the tubes, and thus counteract the tendency of the feed to lower the temperature. (d) Set it the same as on any other engine. Suppose it is the fore gear eccentric that has slipped. Put the engine on the front center and set it in full back gear. Then mark the valve stem with a tram or else scribe the stem close up against the stuffingbox. Then put the lever right over in the fore gear and turn the eccentric around on the axle until the stem comes into the same position as before; get your fireman or one of the brakemen to watch the stem and tell you when the above position is reached. Then tighten up the eccentric. This setting will suffice very well to carry you home. Unlike the Brooks, Schenectady, Pittsburg, and other compounds, the Vauclain has neither receiver nor intercepting valve. (e) Yes. The idea is, of course, to get water into the cylinder and thus gradually arrest the motion of the engine. Better knock the cylinder heads off than have a collision. We, however, would prefer to simply reverse the engine and give her steam, gently at first, using sand at discretion. Why couldn't the engineer in question apply the brakes and stop, even if his pump had failed? If his auxiliary reservoirs were charged, the brakes could have been applied, and if the main reservoir were also charged, the brakes could have been released; if, however, there was not enough air in the main reservoir, he would have had to pump up to get the brakes off. The question, however, was one of simply stopping the train.

M

M

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(447) Can a two-phase motor be run with a threephase current? I am looking after motors in a mine, and wish to know if there is any way to change a three-phase current so as to use it for a two-phase machine. W. L., Eslado Elgado, Mex. ANS.-Connect the primaries of two transformers to the three-phase circuit, as shown in the figure. The connection a should be made just half way between the terminals B and C, or at the middle of the primary winding. This can be accomplished by baring the insulation and soldering on a connection. The three conductors of the three-phase circuit should be connected to A, B, and C, and the twophase motor by means of four conductors to the secondaries M. M.'

a

B

HOME STUDY.

stroke: 38 per cent. of 48,000 (foot-pounds delivered per stroke of the engine) is 17,900 foot-pounds, which is the energy stored in the wheel per stroke. We must find the flywheel that will absorb or deliver this energy without changing speed more than 4 of 1 per cent. The energy stored in a revolving body being equal to one-half its mass, multiplied by the square of its angular velocity times the square of its radius of gyration, we readily find that the above condition is fulfilled by a wheel 16 feet in diameter and weighing 22,800 pounds." Kindly explain how this size and weight are obtained.

S. S., Schenectady, N. Y. ANS. (a) The discrepancies mentioned are typographical errors, and have been corrected in the last edition of the "Mechanics' Pocket Memoranda." (b) G2 = (r12 + r22) = $(d12 + d) where d is the outer, and do the inner, diameter. (c) Referring to the article in question, the speed is 100 revolutions per minute. Denoting the angular velocity by w, this speed gives w 2 X 100. 10.472. To store the required energy, the angular velocity must vary from a minimum we to a maximum w, the increase of energy being, therefore, WG2/uy w2

WG2

2

g where G is the radius of gyration. Now, the average WI + W2 angular velocity is = 10.472, and, from the 2 statement of the problem, the variation in speed is .4 wy + W2 2

of 1 per cent., that is, w1 — W2 = .004 ×

2

Mul

tiplying both sides of this last equation by w12 - wz = .004 X == .004 X 10.472. 2 2 The increase of energy required is 17,900 ft.-lb. Hence, WG w12 W G2 X .004 X 10.4722 g 17,900 X 32.16

ог,

)

WG2=

.004 X 10.4722

1,312,400.

17,900,

(449) (a) How is the low temperature that is required to liquefy air obtained? (b) Has air been solidified? (c) Since air is a mixture of oxygen and nitrogen, why are these gases not liquefied separately and then mixed to form liquid air? Would this method be simpler than the other? (d) How can ink stains be removed from the skin, from paper, from cloth, and from kid gloves, without injury? (e) What is the meaning of a chemical formula such as MgNH,HPO4? Can you tell me of any good book on the subject? (ƒ) Can you mention any good book on artificial illumination?

J. W. S., New York, N. Y. ANS.-(a) This question will be answered, more fully than the space here would admit, in an article on liquid air in a future number of this magazine. (b) Yes; in the form of a snowy mass. (c) No: because oxygen and nitrogen have to be first artificially produced, and consequently two gas-generating apparatus and two liquefying apparatus would be required. (d) Ink stains may be removed from the skin by wetting the skin with water and then rubbing the stains with a piece of citric acid; from paper, by touching the ink stain with a little hypochlorous acid and washing the wetted surface, by means of a sponge, with water. We don't care to give you a receipt for removing ink stains from cloth and kid gloves, as to do this considerable skill and experience is required, or you will destroy either the material or its color; better go to a reliable cleaning store. (c) A chemical formula shows the composition of a compound; the formula you mention shows the