170 Louis Schwendler — On the Em])loyment of [No. 3, 



nienfc was made in order to see whether A or E machine would suit the 

 circumstances best. 



The resistance in circuit was not measured, but may be taken to be 

 the same as given for A. The main current gave a mean deflection oi: 



„ max. 33-7 



' min ~ 270 ' ^^^^'^^ engine = 59 9 revolutions per 



max. UD . . „ 



minute ; — - = — •. The variation of the current corresponds with that 

 mm. 54< ■'■ 



of the speed. 



The results of the preliminary trial are given in the following table : — 



0. of 

 rimerit. 



Mode of pro- 

 ducing- the 

 current. 



Speed of engine 

 per minute. 



Mean speed 

 per minute 

 of dynamo- 



Mean of 

 main cur- 

 rent in 



Current in milli- 

 oersteds. 





Mean, 



Max. 

 Min. 



electric 

 machine. 



milli- 

 oersteds. 



Sent at 

 Calcutta. 



Received 

 at 



A.llahahad 



1 



60 Minotti 









9-8 



9-8 



5-1 



2 



Dyn. el. 

 machine A. 



60-3'* 



621 

 68-51 



783 



36,846 



14-5 



7-7 



3 



Dyn. el. 

 machine E. 



5995 



66' 



sir 



641 



27,991 



9-4 



6-6 



The three experiments were made in the order given. Noa. 2 and 3 

 were made from 11 to 11'44 hours, during which time messages were 

 sent. The insulation of the battery wire L was variable from 71,000 

 to 95,000 ohms absolute. 



Trom Experiments 2 and 3, it will be seen that A machine produces a 

 larger main current than E, which is due to the higher speed of A ; further, 

 that the sent current tapped from the main current of A is larger than the 

 sent current tapped from that of E, just as it ought to be. In fact, if the 

 line during the two experiments had kept constant, and if also r had kept 

 constant (r increases considerably by heating), the proportion of the two 

 main currents would have been the same as that of the two sent currents, 

 and this is very nearly the case.f No. 3 Experiment with E machine gives 

 about the same result as No. 1 Experiment with battery. To produce the 



* The small numbers in the form of exponents mean the number of observations 

 made. 



t ^ main currents = 1"32. 

 A 



— sent currents = 1-65. 



