478 



sent back to its starting-point, while a drum with paper, on which 

 the recording occurred, was moved on 1.5 mm. 



Fig. 2. Top of the clinostat-axis with conical wheels, as described 

 in the text. 



The pen moves along the paper with a velocity of 1 mm. a 

 second, writing a straight line. A number of parallel lines arises 

 in this way, as shown in fig. 4, drawn for so many seconds as the 

 period amounts to, needed by the clinostat-axis to make a half or 

 a quarter of a rotation. 



If therefore the clinostat runs regularly, these lines must be of 

 equal length, or may differ one second at most, with respect to the 

 point of time at which the contact witli the mercury is made. 



In the figure something else has been recorded: every 6 minutes 



