154 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1907. 
operated electrically. The aggregate delay has been less than with 
the old steam service, a fact particularly noticeable in times of snow- 
storms. The main station output for twenty-four hours is but about 
65,000 kilowatt hours, and when the batteries are in service but one 
steam unit is required at time of maximum load. 
The New Haven alternating current-direct current locomotive, 
built by the Westinghouse Electric and Manufacturing Company, is 
of the two-axle free bogie type, the bogies being pivoted under and 
transmitting their effort through the frame which carries the cab, in 
which are mounted the transformers, blowers, rheostats and con- 
trollers (pl. m). On each truck are mounted two spring-supported 
motors, each complete within itself. The armatures are carried on 
quills, terminating in spiders at each end, which engage eccentrically 
wound springs inclosed in pockets in the main drivers. 
The rigid wheel base is 8 feet, the total wheel base 22 feet, and the 
length over all 37 feet. The weight of the locomotive is 93 tons, hayv- 
ing been raised considerably over early expectations. It has an 
hour rating, on the usual standard, of 1,000 horsepower when oper- 
ated at 25 cycles, but 1s equipped with blowers to raise the average 
capacity. It is intended to handle a 200-ton trailing load at schedule, 
with some margin of performance. 
Although built primarily for operating directly from 11,000-volt 
single-phase alternating current, these locomotives must operate also 
from the 650-volt direct current while on the Harlem tracks. They, 
therefore, have additional control provision, and besides the double- 
pantograph collectors, have contact shoes, those on the side being 
arranged for lifting by air pressure on account of limited clearances 
on a part of the run. 
The motor armatures are wound for operation at a normal maxi- 
mum of about 250 volts, and hence are connected in permanent series 
of two, while the field circuits are arranged for each pair of motors 
in a separate group, and for series-parallel grouping independently 
of the armature circuits, to provide for the varying flux in alternating- 
current and direct-current operation. Of course, the two motor 
groups can be connected for series-parallel operation with direct- 
current supply, but with the disadvantage of using about double the 
amount of current at slow speeds that is required when four motors, 
each wound for the full potential, are in series. 
The first of these machines, pulling a short train, made entry into 
the Grand Central Station on May 11, 1907, and in a short time the 
operation of equipment should be under service test. 
In order to combine the possibility of single-phase alternating-cur- 
rent current transmission at high voltage by overhead trolley, and the 
unquestioned advantages of the direct-current motor, it has several 
times been proposed to introduce between the line supply and the 
