CH. VII] KLTNOSTAT. 187 



upper end of the left-hand support s. The spindle is 

 also supported at g on the friction wheel fr. The spindle 

 (with the plant attached) is made to rotate by means of a 

 band of silk dr passing round the wheel w, and also 

 round a pulley on one of the axles of the American watch - 

 action clock c which 1 is attached by means of the screw R 

 to the support s. By passing the driving gear over the 

 large pulley W the spindle is made to rotate once in 30 

 minutes. We find that one turn in 20 minutes, which 

 is the rate given by the smaller wheel w, is a convenient 

 speed. 



When a plant is fixed into the box B it naturally 

 happens that the centre of gravity of the plant and flower- 

 pot does not coincide with the spindle, so that the clock 

 has varying amounts of work to do in different parts of 

 the rotation. The Cambridge Scientific Instrument Co/s 

 klinostat has an arrangement by which the position of the 

 weight can be altered until its centre of gravity is at the 

 centre of rotation. 



The mechanism is shown in fig. 87. The end of the 

 spindle k terminates in a screw sc, which passes through 

 the boss c and the disc-shaped plate d to which the boss 

 is united. As long as the end of the spindle does not 

 press against the brass plate n, the disc (and spindle with 

 it) can slide in any direction parallel to n in a cylindrical 

 cavity sp sunk in the wood plate pi, of which the floor is 

 formed by n, and the roof by the brass plate m. The 

 latter plate is attached to the wooden plate pi, and is 

 pierced by the hole hh. The edges of this hole limit the 

 1 In the figure the clock has been simplified. 



