Page images
PDF
EPUB
[merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small]

Total Value of Complete Outfit, $15.34

One dozen Thumbtacks,

[ocr errors]

Nine sheets Whatman's handmade, cold pressed,
Drawing Paper, 13x20 inches,

Twelve sheets Whitstock Drawing Paper,
inches (for practice work only),

One Nickel Plated Erasing Stencil,
One Sandpaper Block,

One 6-inch German Silver Protractor, 0,
Retail Price of Materials,

[ocr errors]

11x15

1.00

[ocr errors]

$ 8.44 SPECIAL PRICE TO A. S. C. STUDENTS an United States $5.95

and Canada Only)

In order to secure the above special price it is necessary to be a student of the American School of Correspondence. Orders should be sent direct to the address of the manufacturer as given below, accompanied by Post Office Order or by Registered Letter for the amount and a statement that the writer is a member of the American School of Correspondence. Express charges are to be paid by the purchaser (for students in the West and Middle West express charges to CHICAGO will be prepaid.) Address:

A. D. MACLACHLAN, 214 Clarendon Street, Boston

ARCHITECTS' AND ENGINEERS' SUPPLIES

Mention The Technical World.

127

[graphic]
[blocks in formation]
[graphic]

Locomotive Whistle Signals

Question: Railway signals have always been a great puzzle to me until I read the article "A Railroad's Nerves," by Mr. D. A. Willey, in your July issue. I travel a great deal, and have always been a great deal interested in the mechanism. I wish the writer would clear up something else about the railroads-the language of the train whistles.-A Daughter of one of your Subscribers.

Answer: The "language" of the train whistle varies considerably, depending much upon the section of the country where the railroad is built. On some of the smaller lines in the South and West where the towns are few and far between, the engineer has a habit of blowing a long blast just before reaching a village, in order to let them know he is coming, apparently-for there is no other reason. The signal adopted by most of the railway companies for approaching a highway crossing, is two long blasts quickly followed by two short ones, or one long blast and two short ones. This is, of course, a warning signal. Four prolonged blasts mean that a train is approaching a siding, with orders to go upon it. The signal directs the switch tender to connect it with the main track. The same signal, however, is used on some systems to recall the flagman who has been sent back of a train that has been obliged to stop for some special reason. The invariable rule, except on railways equipped with block signals, is to send a trainman back with lantern or flag, to protect the rear end from collision with any train which might be following.

A single, short blast of the whistle usually means to apply the hand-brakes if air-brakes are not used; while two short blasts is the response of the engineer to the signal of the conductor to stop at a station not scheduled on his time card as a stopping place. In freight train service where two engines are employed, a double whistle from the head

Mention The Technical World.

[blocks in formation]

The only Steam Pump manufactured with flat face steam valves having a minimum of clearance (one-eighth to one-quarter inch) in steam cylinder, which will not short stroke nor injure from load to no load, if load is suddenly removed. Made in Direct Steam, Belt and Motor Driven. High Duty, Tank, Air Compressors, Deep Well Heads, Mine, Vacuum, Jet and Surface Condensers, Etc., Etc.

ENGINEERS.-We would be pleased to send you our latest Catalog No. 16

[blocks in formation]

Introduce them in your "followup" and notice increased returns.
WARD & DELAY, 40 Dearborn St. Chi.

STARRETT
TOOLS

[merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small]
[graphic]

L. M. PIGNOLET 84 Cortlandt St. New York

are the standard for accuracy, workmanship, design and finish. Whether you use tools to earn your daily bread

or for amusement and relaxation from a different vocation, it pays to use GOOD tools. You can get a better quality of bread and a good deal more pleasure. Use Starrett Tools.

Send for Catalogue No. 17G. 176 pages, illustrated, free

THE L. S. STARRETT CO.

Athol, Mass, U. S. A.

Mention The Technical World.

RE you BUYING your power or

A MAKING your own?

If you are BUYING, how do you know how much you are getting and whether or not it is uniform?

An AMERICAN RECORDING GAUGE will give you an accurate record, showing the variation each hour of the day or night.

If you are MAKING YOUR OWN power, are you sure that your fireman keeps the pressure steady and does not use more coal than is necessary?

An AMERICAN COMBINED PRESSURE AND RECORDING GAUGE on your boiler not only gives a direct reading, the same as the ordinary pressure gauge, but also records accurately all variations of pressure during the day or night.

[blocks in formation]

CONSULTING DEPARTMENT-(Continued)

engine is a signal to the rear to start up; while three whistles is the usual signal for backing.

A poem explaining whistle signals appeared in our issue for August, 1904 (p. 79).

Power-Factor Meter

Question: What is a power-factor meter used for? Also what do the figures on the dial represent?-IV. L.

Answer: The power-factor meter, as its name indicates, is a meter used to measure the power factor of the circuit, the power factor being the factor by which the apparent watts must be multiplied to equal the true watts in an alternating-current circuit. It is evidently always I, or less. In other words, it never can exceed unity.

Another way to state the matter is that the power factor is equal to the cosine of the angle of lag of the current behind the electromotive force; and it is this cosine of the angle of lag which the power factor meter indicates. When properly connected to the line, it reads directly in terms of this function of the angle mentioned.

[graphic]
[blocks in formation]

Simple and Compound Gear
Locomotives

Question: The TECHNICAL WORLD for April, 1905, speaking of the largest locomotive in the world, says: "The draw-bar pull is 70,000 lbs. working compound; or 80,000 lbs. in simple gear. Kindly explain technical expressions in italics.-R. F.

Answer: When a locomotive is working in simple gear, the steam enters the cylinder, does its work by expansion, and exhausts directly to the stack. When working compound, on the other hand, the steam, after doing work in the highpressure cylinder, passes to a second or low-pressure cylinder, where it expands to a still lower pressure. When working in simple gear, the draw-bar pull is naturally greater, since the high-pressure steam enters both cylinders, instead of only one as in the case of compound operation.

Mention The Technical World.

[merged small][ocr errors][merged small]
[blocks in formation]

High grade screw cutting engine Lathes, 9 to 16 inch swing, with forged crucible steal hollow spindles, phosphor bronze bearings, gear-driven reversible feeds with strong friction drive in apron, patented spring nuts for holding change gears in place and allowing quick shifts. Can furnish Draw-in Chuck, Gear-cutting, Milling and Taper Attachments when desired.

Suitable for electrical and repair work, model makers, gunsmiths, technical schools and fine, accurate machine shop and tool room service. Send for Catalog B.

The Seneca Falls Mfg. Co.

[blocks in formation]
[graphic][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][ocr errors][ocr errors]
« PreviousContinue »