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test, speaks eloquently for the system of maintenance of brakes on the N. C. & St. L. Ry. Tests Nos. 32 and 33 were made by backing the car with the engine until the desired speed was developed, then the angle cock was closed, engine detached and hose uncoupled. The angle cock was opened at a certain point, from which the stop was taken. A comparison of the stops made by the sleeper and the coach will, perhaps, cause a surprise to some readers, and perhaps open up a new line of investigation, which, if followed up, will reduce the number of slid flat wheels had on coaches.-Press and Printing Committee, Proceedings of Second Annual Convention of the Air-Brake Association, 1895.

New British Standard of Weights. United States Consul Boyle, Liverpool, England, under date of November 13, 1903, reports that the British government has taken the first step toward the adoption of the decimal system of weights. It has just been announced by the board of trade that, under a special order in council, it will sanction the use of a weight of 50 pounds, instead of the present standard of 112 pounds (called a hundredweight) and 56 pounds (called a half-hundredweight). The 50 pounds is by this action made a legal standard of weight. This reform has been adopted after forty years of agitation by Liverpool merchants and later on by petitions to the government by the chambers of commerce throughout the country, and particularly by the chamber of commerce of this city. Liverpool has felt the necessity for the change more than any other city, as this is the leading entrepot for American and colonial produce of bulk, the weighing of which is a considerable item in the handling and, indeed, in the ultimate cost of the shipments. More cotton, corn, provisions, and tobacco are imported into Liverpool than into any other city in the world, and by far the largest proportion of these imports come from the United States; so the United States is peculiarly interested in the reform just instituted. The Liverpool Journal of Commerce comments approvingly as follows:

All these great quantities are calculated by the American sellers in pounds avoirdupois, but by the British buyers they have had to be counted in hundredweights, quarters, and pounds, in accordance with our antiquated and absurd and anomalous system of weights. What is the consequence? To give a concrete example:

The buyer wishes to ascertain, say, the weight of 100 pounds of tobacco; to do so the nearest weight he can apply is a added smaller weights until the exact quarter, or 56 pounds, to which must be quantity is ascertained. But two 50pound weights will give him the exact amount at once; three will give him the weight of 150 pounds, four 200 pounds, and so on, smaller weights being used for fractions of 50 pounds. The consequence is an enormous simplification of calculation. It should be remembered that the men who weigh these materials at the docks are not, as a rule, mathematicians who can tell the time of day by algebra. They are largely day laborers, who have not had a superior education, and to weigh quantities with a set of weights necessitating the calculation of fractions of pounds, and thereby the use of dozens of small weights, necessitates a mental effort of which all are not capable, and the use of a multiplicity of weights which confuses them leads to errors and loss of time and time is money. But by the adoption of a 50-pound weight a unit of calculation has been obtained which will sweep away a whole set of weights, prevent errors, and save confusion, time and money. It should be remembered that the present complicated and wasteful method of calculating weights has to be gone through four times-first, when the goods are warehoused; second, by the customs, for the purpose of duty; third, in the counting-house; and fourth, in the factory-and in all these cases the same cumbrous system of calculation by hundredweights, quarters, and pounds has to be gone through, and the loss of time, convenience, and money quadrupled. But by the adoption of a 50-pound weight, though four separate calculations will still be necessary, they can be done simply and quickly. The saving in bookkeeping will alone be great. The present system necessitates a mass of figures of different denominations; but by their reduction to the one common denominator of pounds weight whole columns of figures will be saved and the risk of mistakes minimized.

"Americans have great difficulty in understanding the English system of weights -almost as much as they encounter in trying to understand the English fractional system of coinage. For instance, if you ask a man here how much he weighs he will tell you, say, '11 stone 7.' A 'stone' is 14 pounds; so 11 stone would be 154 pounds, and adding the extra 7 pounds the weight given would be 161 pounds. Even Englishmen 'to the manner born' have to make a mental calculation in arriving at the result in pounds in such a case. Sometimes provisions and other articles are sold at so much a stone, and then if the quantity purchased weighs a few odd pounds over a stone or a number of stones the purchaser and

seller have to figure out the price per pound. It is the hope and expectation that the results from the adoption of the new standard weight of 50 pounds will be so satisfactory that before long the old-fashioned 'hundredweight' of 112 pounds will be entirely abolished along with the stone, and that a decimal fractional system of 5 pounds, 10 pounds, and 25 pounds will come into general use.".

Signal Lamps.

A signal lamp that will burn all night without blowing up, using too much oil or requiring too great care in handling is an article that is needed by many roads. The cost of oil, wicks and burners per lamp per month averages 60 cents in the States east of the Mississippi, and with labor of attendance amounting to as much more, the total annual expenditure for switch and signal lights on a large road amounts to a considerable sum. The ordinary signal lamp is an inefficient device and but a small part of the total light of the flame is made use of. The recent development of the long-time burner and the tests made to demonstrate its efficiency have helped to give lamp users a clearer insight into the principles of lamp construction and the possibility of getting better results with the ordinary lamp.

The important points to be considered in the design and construction of a lamp are: First, ventilation; second, size and focusing of the lens; third, the burner; fourth, material used in construction; fifth, accessibility of the parts, and sixth, interchangeability.

Proper ventilation is the most important thing about a lamp, and unless this is efficiently arranged the light will be poor no matter how large the flame. Air is usually admitted to the interior of the lamp at the top or from the bottom, but with either arrangement provision is made for the escape of the hot air at the top of the lamp. The openings wherever made are arranged with the idea of breaking the force of the draft and interfering as little as possible with the steadiness of the flame. With the bottom draft arrangement it is difficult to keep the flame from smoking. If a scant supply of air is admitted to the lamp the flame smokes and the lens gets dirty. If sufficient air is admitted for combustion the flame is blown about, causing it to smoke, and soot is also deposited on the lens. In

either case the moisture generated by combustion is condensed in cold weather and collects on the lens and sides of the lamp. The efficiency of the lamp is greatly reduced and much labor is required to keep the lens and lamp clean.

The top draft lamp or the one that allows the cold air to come in at the top has been in use for a long time. Unless suitable devices are provided, the incoming cold air mixes with the hot air, interfering with the draft, and while the lamp will do well in winter, in summer the flame will smoke, as it is difficult to get rid of the heat generated by combustion. The use of a cone by which the incoming cold air as it descends is deflected against the sides of the lamp and kept separate from the hot air rising from the flame creates a good circulation and sufficient draft to keep the oil below the flashing point, even in the hottest weather. The cold air passing down the sides of the lamp contains no more moisture than the outside air and no moisture is deposited on the lens. In consequence, the glass lens remains clean and the light is not obscured.

The proper focusing of the lens affects materially the efficiency of the lamp. The rays of light radiate from a flame in all directions in straight lines, and the brightness of the light diminishes directly as the distance from the flame increases. To increase the amount of light thrown in a given direction, the rays radiating in other directions must be bent into lines parallel with the ray going in the desired direction. This bending of the rays is accomplished by the lens. Other things being equal, the lense covering the largest area of the circle will bend the most rays and show the brightest light. While the rays of light passing through the focus of the lens will be bent in the proper direction, those not passing through the focus will merely have their direction changed without being brought together, and will not aid in increasing the brightness of the light when looked at from a distance. Therefore to get the best results with a given flame, the brightest part of the flame must come within the focus of the lens, and if the most economical results are to be had the brightness of the flame in the focus should be increased, and that part outside of the focus reduced as much as possible.

Accurate photometric tests, made under competent supervision, of the light from various burners, when placed behind a 5%-inch lens, are reported as giving the

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flame, 23-candlepower light.

A. & W. or Dressel burner-2.2-candlepower flame, 48-candlepower light. Zenith burner-5.1-candlepower flame, 88-candlepower light.

The small, round flame of the longtime burner, giving a light of 2 candlepower and consuming one-fifth the oil of the flat-flame burners, gives a light equal to 63 candles when put behind the lens. An electric light of 1 candlepower but with small filament, all of which is with in the focus of the lens, will give a light equal to 100 candles. A 16-candlepower electric lamp with but a small part of the filament in the focus of the lens will give a light of only 40 candles.

The focus of a lens, if the surfaces of the glass are perfectly true, is a mere point, but with the molded glass lens used in signal lamps, the focus has an apparent diameter of an eighth of an inch. While the area of the focus is no more than this when measured at right angles with a line through the center of the lens, this area is not materially increased when measured % inch nearer to or farther away from the lens, so that, while the apparent area of the focus is that of circle 8-inch diameter, the focal depth of the lens is about 4 inch. If the flame used in the lamp is a flat one and is placed sideways to the lens, a small cylindrical part 1 inch diameter and inch long is all of the flame that will lie within the focus. If the flame be placed edgewise to the lens a part inch diameter by 4 inch long will be within the focus and more light rays will be bent in the proper direction by the lens, the light from one part passing through the other part of the flame with but little loss. In proof of this, tests show that the increased efficiency obtained by burning the flame edgewise to the lens is about 50 per cent. The Dressel burner then giving a light equal to 103 candles and the Zenith burner 179 candles.

There is little to be said about burners. All using kerosene give a yellow light of comparatively low intensity. The most efficient burner for a lamp having a lens is the one with a comparatively small but intensely hot flame. Users of the longtime burner report that it gives a good light for a short while after trimming, but that it gets dim from the wick charring and the flame smoking. For signals requiring a uniformly bright light a flat

burner will give the best results, but if economy has to be considered and a moderately bright light will be sufficient, the long-time burner may be used to advantage.

The rough handling to which signal lamps are subjected requires the use of heavy material in their construction if the lamps are to last a reasonable length of time. The No. 18 Bessemer sheet steel, of which the body and sides of the best lamps are made, is strong, and if the joints are riveted instead of soldered the lamp will not be injured by anything short of an explosion or a severe blow.

In the care of a lamp, cleanliness is of the first importance, as without this the light of the flame will be obscured and combustion will be interfered with by an insufficient supply of air. As an aid to cleanliness, ease of access to all parts of the lamp is a very necessary feature. If the door of the lamp is not large enough to admit the oil pot and burner without difficulty, the parts will be roughly handled, with occasional injury. If the burner shaft is not carried outside of the lamp body the lampman is apt to put the lamp out without properly adjusting the flame, particularly if there is a strong wind blowing. If all parts of the burner can not be readily cleaned by a piece of waste held in the hand the burner will be allowed to get dirty and gummed with oil and the light will be poor. In fact, all parts of a lamp must be clean if a good light is to be had, and while almost any lamp may be properly cleaned if given the necessary attention, it is not to be expected that the men obtained for the wages paid lampmen will keep the lamps clean if the parts are not easy to get at.

Signal lamps, like most other devices used by a railroad, have passed through various stages of development, and most roads have many lamps in use that are of different sizes, shapes and kinds. A lamp once used for a certain signal is thought by many to be the only one suitable, and the same lamp will be continued in use whether or not another and better lamp may as easily be obtained. Economy in the purchase and use of lamps, as well as convenience in supplying parts can best be secured by reducing as far as possible the number of the different kinds of lamps to be kept in stock. adopting a standard and arranging the brackets of all signals so that standard lamps may be used, the lamps to be kept on hand may be reduced to three patterns: One, the single lens lamp for a

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single-arm semaphore signal; two, the lamp having two lenses to show a light in opposite directions and be used with a double-arm signal, and, three, the lamp used for revolving signals and having two lenses arranged at 90 degrees one with the other.

But two styles of burners need be used with the lamps-the flat burner and the long-time burner. But two oil pots will be required, the long-time burner being shorter than the flat burner and having to be raised to bring the flame in the focus of the lens. By buying new lamps only of the standard design and scrapping old obsolete patterns that can not be repaired at reasonable cost, the advantages to be had by the use of a standard will soon be realized.-Railway Age.

Moving of the Lackawanna
Bridge.

A press dispatch, dated New York, January 7th, says: Few achievements of the engineers of modern times have been more gigantic or more successful than the recent moving of the Lackawanna railroad bridge at Newark, N. J. It was found necessary to move the structure, a heavy steel affair, some fifty feet, and officials desired that as little interruption of traffic as possible should take place. The problem is one that has often been solved, but in this case public attention has been directed to a special method. After the draw span had been lifted from its old position and floated to its new one on barges, instead of lowering it to its bearings by screws or hydraulic jacks, it was lowered by means of "sand jacks." On the barges were boxes filled with sand on which the bridge rested, and the same was allowed to run out of suitable openings in the boxes and so let the bridge down.

This is exactly the method that was used in Egypt 4,000 years ago in placing the huge lintels of the temples on the columns. The stones were dragged by main force up inclined planes formed of bags of sand to a position over the tops of the columns. Then the bags were pierced, and the sand, slowly escaping, let the stone gently down to its bearings.

It is probable that a similar method was used in erecting the obelisks, which we today find difficult to handle with steam to aid us. Just as the lintels, so the obelisk was dragged to the top of the heap of sand bags until its base was over,

but far above the foundation. Then as the sand was gradually removed the base would be lowered until the obelisk reclined in a slanting position on the side of the slope of sand, with its base resting on the foundation. It was, of course, not yet upright, but by far the most difficult part of its erection, the raising of the summit through the lower part of the quarter circle it must describe, had thus been overcome, and it was then but a matter of wedging up the upper end little by little and building up the sand slope until the final position was reached.

Partly to make the turning of the lower edge easier, but principally to prevent its being cracked off, the sharp angles of the base were rounded, especially at the corners. In the obelisk now in Central Park the crabs that seem to support it fill the space made by the cutting away of the corners for the reason specified.

Used in Egypt's Tombs.-In some of the tombs cut in the cliffs that hem in the Nile Valley, as well as in those built in the pyramids, "sand jacks" still more closely resembling those used at Newark can be found. The protection of the chambers that contained the sarcophaguses, while leaving the richly decorated vestibules and passages of the tombs accessible, was one of the most important matters in their construction, and to do this enormous stone slabs, resembling the masonry on each side, were used to close the narrow halls leading to the burial chamber. The slabs were somewhat wider than the full width of the passages and slid in grooves at the side up into a pocket in the roof.

The tomb was built with a slab in place in the pocket, leaving the passage open under it. It was supported by small square columns of stone or wood hidden in the grooves and resting on sand that filled the lower ends of the grooves, which extended down into the floor. Ingeniously contrived channels led from the bottom of the grooves to the outer part of the passage, and when the last sarcophagus had been placed in the chamber the plugs that closed the channels were taken out to let the sand escape. The slab slowly descended until its lower edge rested in a groove in the floor of the passage, and it could then never more be raised, for sides, top and bottom were embedded in the masonry and there was no crack where a lever could be inserted or a hold of any kind be obtained. The slab was usually of such thickness that it gave no indication of the hollowness be

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