LAPSE-TIME PHOTOGRAPHY 37 



chain belt and the device above you are sure the 

 camera shutter is always closed when it stops, and a 

 uniform exposure given. 



Holding the pendulum up is necessary till the 

 shaft that connects with the camera has made its 

 complete turn, otherwise the pendulum would drop 

 down, breaking the connection as soon as the taper 

 pin in the moving wheel, that lifted it, had passed. 

 If the wheel is carefully made with the pins all equal, 

 it will swing the pendulum just a little higher than 

 the point at which it is caught and everything works 

 without a sound and is positive. 



I have made a dozen or more of these lapse-time 

 devices, but this is the simplest and cheapest and can 

 be made to do all sorts of things automatically day 

 and night. If I am running on a long story of three 

 months' duration, like from seed to fruit, which will 

 show on the screen in perhaps a couple of minutes, 

 a second and stronger motor can be connected and 

 if the plants are growing in a greenhouse it can be 

 converted into a dark room. Electric lights come 

 on, giving the uniform exposure day and night, a 

 picture is made, the lights go out, and the dark room 

 becomes a greenhouse, allowing the plants to grow 

 in natural conditions for twenty or thirty minutes 

 and then for perhaps three minutes the chain of 

 operations goes on again, keeping it up day and 



