along the center line of the car, the spacing varying from 4.5 to 10 ft. according to the size of lamp to be used. This spacing is also dependent on the length of the car, as the lamps are operated in series and must be in multiples of five.

When the seats are longitudinal, along the sides of the car, the units are arranged in two rows, about 22 in. from the side of the car. The same spacing is used as with the center lamps.

The lighting system is designed to give a minimum illumination on the plane of utilization of 1.5 foot-candles under conditions of 80 per cent. normal voltage, which means that at normal voltage the illumination will be about 3.75 foot-candles. This variation is a condition which will have to be corrected before street-car lighting can be called satisfactory. Up to the present time no device has been produced which satisfies the operating officials of this class of car as to cost and simplicity.

REFLECTORS AND GLASSWARE

A number of types of reflectors and enclosing units have been developed for car lighting uses.

For coach lighting, and other classes of cars where efficiency is the prime object, and appearance a secondary consideration, the openmouth reflector is in almost universal use. Best results are obtained with a reflector giving the maximum candle-power at 45°.

The following are the principal types of this class of reflector, together with the illumination obtained and the efficiency using a 6-ft. spacing, giving 66% generated lumens per running foot of the car:

Where appearance is the primary consideration enclosing units are used, and the energy efficiency somewhat sacrificed.

The following results are obtained with this class of unit under conditions similar to those stated above:

All of the foregoing are for electric light. For gas lighting the following results were obtained, the generated lumens being 130 per running foot of car:

Aluminized metal reflectors are in very general use in postal and baggage cars due to their high efficiency and durability.

FIXTURES

Lighting fixtures for use in railroad cars require special design and construction, and embody some features not found in fixtures built for other purposes.

1. They must be substantial to withstand the constant vibration to which they are subjected.

2. They must be easily removable for refinishing when the car goes through its regular shopping.

3. The arrangements for holding the glassware must be such that

it can be easily applied, or removed for cleaning, but at the same time must be securely held so that there is no danger of its jarring loose.

4. They must be of suitable color and design to harmonize with the interior treatment of the car.

5. The mechanical design must be simple and all working parts must be easily accessible.

The first condition is met by careful mechanical design, suggested by experience in this class of work, as fixtures built for other uses are wholly unfit for use in railway cars.

The second feature is generally covered by a type of construction in which a plate or spider is firmly fastened to the car ceiling, this plate forming the support for the socket. The ornamental part of the fixture is secured to this plate, but may be removed without disturbing the electric connections or the attachment to the ceiling.

The arrangements for holding the glassware in enclosing units must be worked out for each type of glass employed. With a large proportion of the fixtures for electric lighting use is made of open mouth reflectors and for these, holders have been developed which fulfill the condition admirably. The ordinary type of holder equipped with set screws was quickly abandoned as being unsafe. One of the best holders developed consists of a spring clamp comprising a number of metal fingers which spring over and grip the neck of the reflector. In order to make the action of this spring clamp positive, a cap nut is screwed down against the spring clamp, locking the fingers against the neck of the reflector in such a manner that the spring of the clamp takes care of expansion in the glass and cushions it against vibration.

The question of suitable design is one which is governed to a certain extent by the wishes of the purchaser, but I believe that the results obtained. in car lighting work compare very favorably with that in other lines.

Electric lamps are built so that the bulbs may be easily renewed, and the sockets and wiring easily accessible. Gas lamps are made so that they can be lighted without opening the bowl, mantles applied without the mantle being removed from the container until it is properly attached to the lamp, and no adjustments to the air or gas supply are necessary; in fact the lamps are made without any means of adjustment.

Much remains to be done before the lighting of railway cars will be all that can be desired, but I know of no other field where more effort is being expended to obtain proper and adequate illumination.

THE LIGHTING OF YARDS, DOCKS AND OTHER

OUTSIDE WORKS

BY J. L. MINICK

It is a notable fact that illuminating engineers generally have given only casual attention to the field of lighting in railway service and it is largely with the hope of stimulating interest in this field that this lecture has been prepared. Probably no other single industry offers such a wide variety of interesting problems for solution in which practically every known form of illuminant may be used to advantage. This field is open to the illuminating engineer if he will avail himself of the opportunities offered. Many railroads of importance have large engineering organizations but only a few employ men. sufficiently well trained in this important branch of science to solve properly the many problems that constantly arise. Many of these problems are common to other industries which have come within the range of the illuminating engineer and their solutions are therefore well known. Many others are peculiar alone to railway service and it is from among these that the material for this lecture has been selected.

American railroads derive approximately three-quarters of their gross income from the handling of freight and about one-fifth from passenger service. All problems whose solution will in any way, improve, facilitate or stimulate the movement or handling of either freight or passengers, are of prime importance to the railroads in their endeavor to furnish adequate service to the public. The lighting of yards, docks and other outside works has been selected for review in this lecture as these problems are intimately connected with the handling of transportation and their importance is not generally well appreciated.

In presenting these problems it must be understood that the solutions suggested are not to be considered as final or conclusive. They represent the labors and investigations of only a limited number of engineers during the past five or six years. Improvements in illuminants and in the control of light are constantly removing many of the difficulties commonly encountered and the investigations of