90 Hough — Mechanical Equivalent of the 



dx 









= C.A 



but 



A = Xy 

 = QjSjf 



where y = average ordinate 

 S = n . 2irr 



where n = no. of revolutions 



y 



r == radius of disk 



where io 2 = total weight of paper 

 w 1 = weight of A 

 I = width of paper 

 G 



where g = ace. due to gravity 

 G == mass in grams to 



displace marker 1" 



cm 



W 



The constant G is determined by empirical calibration, for 

 which four steps are necessary : the calibration of the scale of 

 one of the pendulums in grams per centimeter by suspending 

 weights in a pan from the pulley : the adjustment of the mass 

 of the other pendulum bob to the same grams per centimeter : 

 the adjustment of either tape until any deflection of the disk 

 gives the same displacement on both scales : the calibration of 

 the marker in terms of these scales. This determines G. 



A second set of observations is taken using a second cylinder 

 of different conductivity capacity from that of the first and L 

 is determined from the following relation : 



where ?/ x = heat in ergs to the rubbers 

 u^ — heat in ergs to water 

 R = heat in ergs radiated 



if the temperature of the shield approaches 



that of the cylinder 

 R = O and 



W = U l + M 2 



but « a =(m + m / )L 



where m = apparent loss of 

 water in the cup 

 m' = water deposited 

 on cup due to 

 water vapor in 

 steam 

 and if m =0 



W = w, +mL. 



