ISO 'Automatic Control of the Flozv of Gas 



point, the projection lifts the fork until the platinum points dip into 

 the mercury, when a new contact is made and the current is sent 

 through the opposite electromagnet. This now pulls the frame and 

 shuts off the gas-flow. As soon as this contact is broken, the mini- 

 mum oxygen delivery (which has been originally adjusted) is once 

 more estabhshed. It will be observed that very little electric power 

 is wasted in this process, as the current passes only at the time of the 

 contact, which, in either case, is immediately broken. 



In Plate 2 the entire apparatus is shown with the electrical con- 

 nections. I use the street current directly and, by the use of a tele- 

 phone condenser of 2 micro-farads (i) across the binding posts of 

 each magnet and one ordinary lamp (2) in series, the contacts are 

 made without any sparking. As the circuits are used alternately, 

 the two magnets are supplied from the same socket (7). 



While the apparatus here described has a definite purpose, it is 

 evident that it may be employed with advantage for other functions. 

 It would be an easy matter, for instance, to utilize the expansion of 

 mercury for making the contacts and thus regulating the flow of 

 lighting gas foi* the heating of incubators or drying ovens. 



