314 Application of Hydraulic Power to Mercurial Pumps. 



to the head of the piston by means of a leather band, I, which 

 passes over a pulley. A flexible tube, T T, connects this to 

 the globe 0. The tube D F leads to the drying tubes and 

 vessel to be exhausted. E is a barometer-gauge dipping into 

 the cistern J, which can be adjusted by means of a screw, so 



that the level of the mercury can be brought to the bottom 

 of the scale, G. M L is a full-sized section of the glass-faced 

 valve at the top of the globe C. A projecting arm from the 

 piston embraces a long rod which actuates the valves of the 

 motor. 



The framework is not shown, for the sake of clearness. 



XLI. On some Electrical Phenomena provoked by Radiation. 

 By Professor A. Righi *. 



IN seeking for an explanation of the phenomena recently 

 described by Hertz f , by E. Wiedemann and Ebert $, and 

 by Hallwachs §, I was led to study the action of light on 



* Preliminary notice communicated by the Author, having been read 

 before the R. Ace. dei Lincei, March 4, 1888. 

 t Wied. Ann. xxxi. 1887, p. 983. 

 X Ibid, xxxiii. 1888, p. 241. 

 § Ibid, xxxiii. 1888, p. 301. 



