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the storage of the material used in the shops above. The equipment of the gas engine laboratory comprises a 35-H. P. three-cylinder verticle gas engine built by the Westinghouse Machine Company, a Fairbanks, Morse & Co. 7H. P. gas engine, a Rider-Ericsson hot air engine, a new Mahler-Baum calorimeter, a Junker calorimeter, a large meter for measuring air, a motor and blower to deliver air at atmospheric pressure, a two-stage air compressor, and various calorimeters for determining the heat values of fuels. On the first floor of the new building is located the Forge Shop, the equipment of which includes thirty down-draft forges, a 200-pound steam hammer, and a power hammer, a coke furnace, a 20-inch drill press, and a 15-inch double emery grinder. A jib

CORNER ELECTRICAL LABORATORY

crane is arranged to serve both hammers with the heavy work. At one side of the Forge Shop are seven benches with complete equipment for pipe fitting. The Machine Shop occupies the second floor, and is equipped with thirteen engine. lathes, three speed lathes, B. and S. universal grinder, a B. and S. cutter, a B. and S. cutter and reamer grinder, and a Diamond grinder. There are three milling machines, a screw machine, a 30-inch planer, two shapers, a horizontal boring machine, a twist-drill grinder, a lathecenter grinder and several drill presses. At one end of the shop are thirty bench vises, with complete sets of tools.

In the Carpentry and Pattern-making Shop on the third floor are thirty-three 12-inch wood lathes, an 8-inch pattern lathe, four 6-inch pattern lathes, a circular saw, two band saws, a 26-inch surfacer, vertical boring machine, a threeside 4-inch moulder, scroll saw, and gluing bench. The shop is also equipped with forty benches, with vises and com

The Foundry is piaced on the top floor, principally for the reasons of providing for the quick removal of gases and smoke, to avoid the heat that would result from its being placed below other rooms, and to secure the overhead light. It is provided with a Whiting cupola, a set of forced-draft brass furnaces, and a portable core oven. There are three one-ton cranes running through the foundry, with a 5-inch air hoist on each. The equipment also includes three moulding. machines and a pneumatic sand sifter. A system of tracks is arranged to carry the metal on trucks from the cupola to the moulds in different parts of the foundry. The demonstration rooms are a special feature of the building. There is one room on each floor with a seating capacity of about forty students, and in each room there is the type of machine to demonstrate how the particular work of that shop is to be done. Ample provision is also made on each floor for lockers and lavatories.

The shops are used by the students of all engineering courses, and by the evening classes four evenings each week. The shop courses are very popular with the students of the evening classes, and the enlargement of the scope of the Institute to include these courses in its curriculum marks one of the most important epochs in its history. No student who applies for admission to the Armour Institute of Technology need be turned away on account of lack of preparation. If he is insufficiently prepared to enter the College of Engineering, he can get this preparation in the Scientific Academy, or, if he is employed during the day, he can avail himself of the opportunities of the evening classes. Should it happen that he lives too far away to take advantage of any of these courses, he can obtain his preparatory requirements in the American School of Correspondence.

The careful working out of these broad plans for the purpose of giving young men an opportunity to secure a technical education, is due to their steadfast friend, President Frank W. Gunsaulus, who, in co-operation with the trustees and faculty, leaves nothing undone to help every aspiring and earnest student to the realization of his plans

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SHADE LINES ON DRAWINGS

O make drawings easier to read, and to make the parts of the object stand out more clearly, shade lines are often used. The general principle which determines what lines shall be shade lines is the same as that which governs shade lines in orthographic projection. If, however, this theoretical principle were to be followed out exactly on drawings of machines and other complicated objects, it would involve a great deal of time and labor. Consequently, most draftsmen place shade lines on all lines which represent lower and right-hand edges.

The contour lines of cylinders, cones and other rounded surfaces should not be shade lines, although some draftsmen

PLAN

the shade lines come on the upper and left-hand sides of the hole, since these lines are the lower and right-hand edges of the material which surrounds the hole.

Fig. 3 is a plan and side view of a rectangular prism with one corner rounded, and with a cylinder resting on it. Here the lines A B and C D are not shaded,

回目

FIG. 2.

since they are the contour lines of curved surfaces. In the plan view, the lower right-hand part of the circle, between X and Y, is shaded. To find these points X and Y, draw two lines tangent to the circle and making an angle of 45° with

X

A B

ELEVATION

FIG. 1.

shade them. If the cylinder is drawn in cross-section, however, the edge should be shaded, as the intersection of the plane and cylindrical surface is a sharp edge.

All views are shaded alike, and both are shaded as though they were elevations. The ray of light is supposed to come over the left shoulder of the draftsman as he faces the paper, at such an angle that the projection of the ray of light on the drawing paper is in the direction of the arrow in Fig. 1.

Figs. 1 to 8 show some of the most common shapes met with in drawings, and illustrate how the shade lines are placed on each. Fig. 1 is an elevation, plan, and side view of a rectangular prism with a smaller one resting on top of it. Fig. 2 is a plan and side view of a rectangular prism with a rectangular hole through it. It is to be noticed that

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exhaust lap, which, by closing the port before the end of the stroke, imprisons the steam, and the moving piston compresses it. The direct-acting pump has no crank, and the valves have no exhaust lap. The cushion is obtained at each end of the cylinder by the use of a small valve which puts the exhaust port in communication with the steam port. Let us consider the action of the cushion valves to be as represented in the accompanying diagrams.

In Fig. 1, the cushion valves are closed.

the piston makes a much longer stroke. By regulating the cushion valve, the length of the stroke may be varied considerably.

B

FIG. 2.

The cushion valves are simple valves worked by hand. Figs. 1 and 2 show the by-pass action; but the actual con

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FIG. 1.

The exhaust steam flows through the exhaust port A to the exhaust cavity C, and escapes to the exhaust pipe. This continues until the piston passes port A. The steam now in front of the piston cannot escape, and is compressed in space B and the port, thus stopping the piston before the end of the stroke.

When the cushion valve is open, as shown in Fig. 2, the exhaust steam continues to escape after the piston has passed port A, by flowing from the steam port through the by-pass as indicated by the arrow. As nearly all the steam thus escapes, there is but little cushion and

FIG. 3.

struction is more nearly like that shown in Fig. 3, which represents the ports, valves, etc.

The latest type of British submarine lutions, the submergence usually boat, built by Messrs. Vickers Sons & lasts three hours; but quarters are Maxim, has a speed under water of be- very cramped and the crew is obliged to tween nine and ten knots. It is a modi- keep fixed stations, as the displacement fied development of the Holland type, of the center of gravity might cause the the length of the new boats being 150 boat to take a disastrously deep plunge. feet (it was 120 feet in the original). It has been suggested that three sets of The radius of action in the new type these boats should be provided, each of is 500 miles (in the Holland it was which would have three days on duty and about 300 miles). The weight is too six days off, in order to preserve the great to permit the boats to be car-health of the crew. The results of offiried on shipboard. In practice evo- cial tests will be watched with interest.

SULPHATING OF STORAGE

BATTERIES

ITS CAUSE AND REMEDY

O

NE of the most serious troubles which occur in storage batteries is sulphating. This can usually be avoided or cured by proper treatment if it has not gone too far.

The normal chemical reaction which occurs in storage batteries is supposed to produce lead sulphate (PbSO) on both plates when they are discharged, their color being usually light brown and gray, due to presence of the PbO, still on the positive plate. But under certain circumstances a whitish scale forms on the plates, probably consisting of Pb, SO. Plates thus coated are said to be "sulphated." This term is, therefore, somewhat ambiguous, since the formation of a certain proportion of ordinary lead sulphate (PbŠO1) is perfectly legitimate; but the word has acquired a special significance in this connection.

A plate is inactive, and practically incapable of being charged, when it is covered with this white coating or sulphate, as it is a non-conductor.

The conditions under which this objectionable sulphating is likely to occur are as follows:

(a) A storage battery may be overdischarged, that is, run below the limits of voltage specified, and left in that condition for several hours.

(b) A storage battery may be left discharged for some time, even though the limits have not been exceeded.

(c) The electrolyte may be too strong.

(d) The electrolyte may be too hot (above 125° F).

(e) A short circuit may cause "sulphating" because the cell becomes discharged (on open circuit), and when charging it receives only a low charge compared with the other cells of the series. A battery may become overdischarged or remain discharged a long time on account of leakage of current due to defective insulation of the cells or circuit; or the plates may become short-circuited by particles of the active or foreign substances falling between them.

Sulphating may be removed by carefully scraping the plates. The faulty cells should then be charged at a low rate (about one-half normal) for a long period. In this way, by fully charging and only partially discharging the cells for a number of times, the unhealthy sulphate is gradually eliminated. When the cells are only slightly sulphated, the latter treatment is sufficient without scraping; when the cells are very badly sulphated, the charge should be at about one-quarter the normal rate for three days.

Adding to the electrolyte a small quantity of sodium sulphate or carbonate, which latter is immediately converted into sodium sulphate, tends to hasten the cure of sulphated plates by decomposing or dissolving the unhealthy sulphate. This is not often used in practice, as a cell must be emptied, thoroughly washed, and fresh electrolyte added after the plates have been restored to their proper condition, before the cell can be used to advantage.

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