ANNUAL ADDRESS. XIX. 
speed is from seventy to one hundred revolutions per minute, but 
where the generator is driven by belting a much higher speed 
is usually adopted. 
A reduction in speed must imply a reduction in weight if the 
same output and degree of general merit are to be obtained, and 
an increase in the first loss ; but this is compensated for by the 
losses of energy due to belting, the trouble saved in bearings, cost 
of maintenance, and other objectional features familiarly associated 
with belt driven generators. Each system has its advocates, but 
the direct driven generators appear to be in more general favor. 
As an example of belt driven generators, one of the most 
modern plants occurs in the Power Station of the Hartford Street 
Railway, Conn. Here the engines are six in number, ‘of the Ball 
and Wood type, working at a high speed and developing 300 H.P. 
Each engine is connected by belting to a generator of 220 K.W. 
capacity ; the distance from the centre of the fly-wheel to that of 
the generator pulley being twenty-five feet. The advantage of a 
large number of units is claimed to be, that with the varying 
loads existing in electric railway service, those engines which are 
in use can be operated at full load, and consequently at their 
Steatest point of economy. 
As an example of slow speed engines directly connected to 
Senerators of large capacity, we may take the Delaware Avenue 
Power Station of the People’s Traction Company, Philadelphia. 
There are at present three engines, each of 2,000 H.P. of the 
twin compound tandem Corliss type, manufactured by Edward 
®, Allis Co., and the speed is sixty-seven revolutions per minute. — 
The generators are 1,500 K.W. capacity made by the General 
Electric Company, and the armatures are keyed to the crank shafts 
of the engine. An advantage claimed for this system, which 
consists in reducing the number of units and increasing their size, 
is that there are hiwer units and fewer parts to look after, and 
Consequently there is a reduction in the cost of maintenance— 
in the economy in using eee engines of the Corliss type is 
well understood and appreci 
