574 



STATE BOARD OF AGRICULTURE. 



vanonieter circuit wKliont ruillicr cliiiiijic. In a jtrevious part of this 

 paper reasons were uiveii lo sliow that no errors but what could be cor- 

 rected could arise from I he use of lliis fie(iuency. The converter and its 

 h-ausfoniier were stored away under Ihe (able ami kept frcuu the jj;alvan- 

 tuueter so tliat tlie latter would not be ex])osed to any extiM-nal electric 

 field, Underneatli and at the side of the table within easy reach of the 

 operator a switch an<l starting box was placed. It was deemed advisable 

 to use a starting box so as to avoid any injury to the rotary converter 

 through overloading. 



Source of alternating current. 



Fig. 8. 

 1. Rotary converter. 



Transformer. 



-DETECTOR. 



The instrument used to determine when a balance had been found was 

 an alternating current galvanometer of the electrodynamometer type, 

 first suggested by Prof. Rowland in 1897. This galvanometer was made 

 by the Leeds & Northrup Company and has proven very satisfactory. 

 Fig. 9 shows the scheme of connections. The fixed coil of the galvanom- 

 eter is placed in the main circuit to increase the sensibility of the appa- 

 ratus. The swinging coil is connected across the bridge in the same 

 manner as with the telephone in the Kohlrausch method. The resistance 

 of the fixed coil is 29.8 ohms and the maximum allowable current is 1/5 

 of an ampere for 10 second periods. By throwing on the 6 volts from the 

 transformer this value of the current is just reached. The resistance of 

 the swinging coil is 21.8 ohms and the maximum allowable current is 



