RECORDS. 199 



tem. The vessel in which the discharge was produced con- 

 tained electrodes which were connected through a galvanometer 

 to a source of E.M.F. of 220 volts. When the discharge passed 

 in the vessel, the gas became a good conductor. The conduc- 

 tivity as indicated by the galvanometer was found to depend on 

 the pressure of the gas somewhat. That is, when the pressure 

 becomes so low that the white discharge appeared, the conduc- 

 tivity increased to near a maximum. It remained nearly con- 

 stant until at a low pressure the discharge disappeared, when 

 the conductivity became zero. 



The absorption of energy was measured by placing a hot- 

 wire galvanometer in the circuit leading from the jars to the 

 coil surrounding the vessel. The oscillating current passing 

 through this galvanometer and coil can be expressed by 



c = Ae-'^^ cos //. 



The greater part of the energy is dissipated in heating the 

 gas and the vessel. The energy will be proportional to the 

 square of the current, while the galvanometer reads current 

 direct. Hence 



Readings 1 e~'^'^^ cos, ptdt. 

 Jo 



Keadmgs oc — ^^ ^,, 



Readings « -. 



That is : a certain reading is obtained without the vessel in 

 the coil. When the discharge passes in the vessel, the read- 

 ings drop back to a smaller value. This drop-back is pro- 

 portional to the dissipation q in the circuit. The energy 

 absorbed reaches a maximum near the pressure at which the 

 discharge first appears. It steadily decreases and becomes zero 

 again at the pressure at which the discharge disappears. 



The measurements discussed by Dr. Poor are made for the 

 purpose of classifying the yachts and furnish a basis for handi- 

 capping them in racing. From such measurements, made of 



