CEETAIN INDICATING AND EECORDING APPAEATUS. 137 
matelj any of the trigonometrical ratios and to explain their 
meaning. Suppose the cosecant of 35° 7' be required 
then in the sine form make a = 35° 1'. 
Turn roller C through one revolution 
then number of revolutions by J5 = cosec 35° 7'. 
There are, no doubt, other applications, if the practical 
difficulties of the problem can be overcome. 
