Registering and Printing Barometer. 



5 



without being cleaned ; it being only necessary to add a 

 little sulphate of copper and water from time to time, to 

 supply the necessary waste. The only power demanded 

 of the electro-magnets is the unlocking of the mechanism, 

 which is driven by weight power. 



Fig. 1. 



In fig. 1, we have a sectional view of the lower leg of 

 the siphon, showing the principle on which this method 

 is based. It may be necessary to remark, however, that 

 the electro-magnets and battery do not occupy these posi- 

 tions in reality, but are placed here for convenience of 

 illustration. 



