Cc. 0. BURGE. _ LXXXVII. 
To ascertain the principal requirements, both firms made 
certain experiments, in the shops, to ascertain the amount 
of the two resistances, friction and air which would have 
to be overcome at the proposed speed. It was determined 
that 10 fds. per ton would be the rolling friction, though 
not much information was given as to how this was arrived 
at. Astotheair, the Siemens and Halske Co. constructed 
an experimental fan, details of which are given in the paper, 
which, driven at the rate of the proposed speed, showed 
that about 185 ibs. per square foot in still air, would be 
encountered, this amounting to just double the resistance 
of the rolling friction. These results showed that 950 HP. 
was required to maintain full speed, so that 1,000 HP. was 
fixed upon for the motors, but they were designed to be 
capable of three times this for a short time, to provide for 
starting and accelleration. 
The body of the cars, which is bevelled top and sides, at 
each end, to diminish air resistance, is divided into end 
platforms for the driver, a central compartment for the 
transformers and other electrical equipments, and the two 
intermediate spaces are cross-seated for 50 passengers. 
The brakes were on the Westinghouse system, but for 
emergencies the electric current was made available. 
The principal differences between the two cars were in 
the following details: the A.H.G. car collected the current 
by two sets of three sloping rods, differing in length and 
inclination, each set swivelling from the roof over each of 
the two bogies. Contact was made with each of the 3 
wires, which were in the same vertical plane, by bows at 
the end of each pole, the pressure being maintained by 
springs. There being two sets of poles, there were there- 
fore six contacts. 
The three-phase current was led to the two transformers 
at centre of car, and, after reduction to a suitable voltage, 
