or seventy miles.  In future experiments the two dynamos will be placed in their normal positions at each end of the line.  The generating machine is driven by a locomotive engine; the resistance of its field magnets is 5.68 ohms, and of the two armatures 33 ohms.  The resistance of the two armatures of the receiving machine is 36.8 ohms, and the resistance of the line is 97 ohms; the generator and receiver field magnets are excited each by a separate machine.  Five different trials were made at varying speeds of the driving shaft; the initial work on this shaft was measured by a dynamometer, and the available energy of the shaft of the receiving machine was ascertained by a Prony brake; the other results of the experiments were deduced from the constants of the machines and from galvanometric measurements.  For the first trials the different elements were as follows: 

1. Generating dynamos:
  Velocity of shaft 123 revolutions. 
  Electromotive force at terminals, 3370.25 volts.
        " " total 3624.7 "
  Available work at driving shaft. 43 h. p. 
  Electrical work of generator 37.38 "
  Difference absorbed 5.62 "

2. Line:
  Work absorbed by the line. 7.59 h. p.

3. Receiving dynamos:
  Velocity of shaft 154 revolutions. 
  Electromotive force at terminals, 2616.25 volts.
        " " total 2336.94 "
  Electrical work of receiver 24.10 h. p. 
  Available work on shaft 22.10 "
  Difference absorbed 2 "

The duty obtained would thus be 22.10/43 = 51.3 per cent., if the work absorbed by the exciting machines be not considered.  Taking this into account, it would be reduced to 40 per cent.

In subsequent experiments the speed of the generator was increased gradually.  In the last trial the following were the elements: 

1. Generating dynamos:
  Speed of shaft 190 revolutions. 
  Electromotive force at terminals 5231.25 volts.
        " " total 5469.75 "
  Available work on driving shaft, 62 h. p. 
  Electrical work on generator 53.59 "
  Difference absorbed 8.51 "
  Work absorbed by armature 2.33 "

2. Line:
  Work absorbed by conductors 7.21 h. p.

3. Receiving dynamos: 
  Speed of shaft 248 revolutions. 
  Electromotive force at terminals 4508 volts. 
  Electromotive force total 4242.67 "
  Electrical work of receiver 41.44 h. p. 
  Work measured on receiver shaft 35.8 "
  Difference absorbed 5.64 "
  Duty obtained, not including exciting machine 57 per cent. 
  Duty obtained, including exciting machine 48 "