100 



DECHERY S CAUTERY. 



the platinum- point or head. The instrument is now ready for use, 

 and will continue acting for twenty minutes to half an hour by simply 



working the bellows. Should the 

 heat decline, a slight turn of the 

 lower stop-cock will admit more 

 benzoline vapour and restore the 

 required temperature. If employed 

 in the open air some precaution is 

 required when starting to shield it 

 from draughts. A point of con-, 

 siderable importance is to obtain the 

 right kind of benzoline ; the com- 

 mon benzoline sold in oil-shops for 

 use in cabmen's lamps or in the 

 little cheap night lamps seems to 

 answer best. 



The second instrument shown 

 i (Fig. 210) is quite different in 

 principle from that of Paquelin, and 

 has the great advantage of being 

 automatic in action when once 

 started, and of requiring no bellows. 

 Every one has probably seen the 

 flaring, roaring lamps used in carrying 

 on railway works, large building 

 operations, etc., at night ; the roar- 

 ing noise and the intense light dis- 

 tinguish them from others. Dechery's 

 > cautery is a modified reproduction 

 of one of these. It may be divided 

 into reservoir (aa), vapour-chamber 

 (b), and burner. The illustration 

 shows these, the essential portions 

 of the interior being indicated by 

 dotted lines. 



To resist the considerable pres- 

 sure at which it works, the instru- 

 ment is strongly made of nickel led 

 brass. The reservoir is shut off from 

 the vapourising chamber by a conical 

 valve, worked by means of a long spindle (c) carrying at its extreme 

 end a milled nut. The vaporising chamber consists of a small 



Fig. 216. 



