Oct. i8, igis 



Automatic Transpiration Scale 



127 



record on account of the double offset, but is difficult to determine in a 

 record of the ordinary type. 



Protecting case. — A tight weatherproof case inclosing the column 

 and beam of the balance protects the automatic equipment from the 



Fig. 13. — Dashpot for preventing the oscillation of the beam during 

 windy weather. 



weather. The case is equipped with a removable top and a sliding front. 

 The latter is also supplied with a smaller door through which the appa- 

 ratus can be observed and adjusted. 



Fig. 14. — Spring motor, showing the cam K for raising the beam, and 

 the fan F for regulating the speed. 



Electric circuits. — The electrical connections consist of three cir- 

 cuits (fig. 17). A single dry cell, B^, operates the relay through the beam 

 contact. The ball valve and the motor release are connected in parallel 

 in a second circuit, B^, containing a battery of three or four cells. This 



