ELECTRIC TRUNK-LINE OPERATION—SPRAGUE. 153 
yokes concentrically with the commutator, are carried on arms at- 
tached to the field-magnet frame, and although moving with it func- 
tion perfectly. 
The electrical and mechanical construction is, therefore, reduced to 
an acme of simplicity never hitherto attained in electric locomotives, 
for not only are there no gears, but there are no armature or field bear- 
ings, quills, driving spiders, or special spring connections, although 
all the weight of the motors except the armature is spring supported. 
The air gap is very large, and as the pole pieces are very nearly flat 
a complete axle unit with its armature can be readily dropped out 
and replaced without disturbing the balance of the motor equipment. ° 
This type of machine, of course, can not be used with any form of 
alternating-current directly, no matter what the frequency. 
When first proposed the design was considered so radical that its 
choice met with a good deal of criticism, but experimental trials 
extending over two years, with 67,000 miles of operation, amply 
demonstrated its remarkable reliability and efficiency, qualities con- 
firmed by the operation of thirty-five of these locomotives now de- 
livered and in regular service. 
The total weight of the locomotive, -without heating equipment, is 
about 95 tons, of which 70 tons is on the drivers. The nominal ca- 
pacity, with 75° rise and natural ventilation, is 2,200 horsepower, at 
which output with 600 volts the motors run at 300 revolutions, corre- 
sponding to 40 miles an hour. The rigid wheel base is 13 feet, the 
total wheel base 27 feet, and the length over all 37 feet. 
The individual control is the series-parallel bridge method, Sth 
resistance variation, the grouping of motors varying from four in 
series to four in multiple, and current is taken from the under- 
contact rail by side-extending spring flipper shoes. 
The exigencies of service are responsible for a recent remarkable 
test. On April 26 the Lake Shore Limited, north bound, consisting 
of nine heavy Pullman cars hauled by a Central-Atlantic type of 
steam locomotive, was stopped in the tunnel under Sixty-sixth street, 
on a 0.5 per cent upgrade, because of some mishap to the en- 
gine. Following it was a train of seven standard day coaches, shop- 
bound and hauled by an electric locomotive, which promptly coupled 
on to the leading train, and without any assistance from the steam 
locomotive, which was dead, started the entire load of sixteen cars 
and two locomotives, weighing nearly 1,000 tons, with good acceler- 
ation, and made the run up a 1.02 per cent grade, a half-mile long, at 
satisfactory speed and without difficulty. 
The New York Central equipment has been developed under extra- 
ordinarily difficult circumstances, but already 305 train movements, 
representing 86 per cent of the present total of the New York Central 
and Harlem trains, both locomotive-drawn and multiple-unit, are 
