98 



lever to the block when it has been displaced from the vertical, 

 say from 0.5 to 1.5 cm., according to the length of the lever and 

 of the record. The arrangement of thread and weight was chosen 

 because, with a little adjustment, the lever may thereby be pulled 

 back quietly and quickly without shock or vibration, after it has 

 been moved by the minute-spindle arm. To set up such an 

 apparatus one may proceed as follows : Take a box, a wooden 

 packing- or mailing-box of suitable size, say approximately a 

 cube, 1 5—20 cm. on a side, fill it with gravel and nail it up. 

 This makes a good, solid stand. Its solidity is enhanced by 

 gluing on the under side as feet, three bits of thin cork. Upon 



Fig. i. 



the top of this stand is affixed a cheap clock from which the 

 glass face has been removed. Its minute-hand must be suitably 

 bent in an L, or in its place an L- shaped arm affixed to the 

 spindle, so that during its rotation, it will move against a 

 shoulder or pin on the record lever. This lever is a wooden 

 arm on an axis attached to the side of the stand below the clock. 

 A little care must be given to adjusting the axis — a wire nail 

 serves very well — so as to avoid any lateral shake. The 

 shoulder or pin upon which the minute-spindle arm plays should 

 be arranged so that the record lever will be moved but a little 

 distance, and then be released. It will then be drawn quickly 



