CH. VIl] 



KLINOSTAT. 



171 



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

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

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

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



Fig. 34. Exp. 217. Copied from the Linnean Society's Journal, 1880. 

 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 con- 

 venient 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 

 kliaostat has an arrangement by which the position of the 

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

 centre of rotation. 



' In the figure the clock has been simplified. 



