LANTERNS AND THEIR MANIPULATION ICQ 



in the plugs may need considerable enlarging. Some years 

 ago no tolerable result could be got from the lantern in use at 

 the then Victoria Coffee Tavern. After doing what I could 

 with the jets, the light was still greatly insufficient for the 

 long-screen distance of 70 ft., with a disc of 20 ft. diameter, 

 dud on examining the * star ' dissolver I found the apertures 

 and channels ridiculously small. I enlarged them to rather 

 more than double their former area, after which the light 

 was quite satisfactory. The bye-pass of a tap may also need 

 alteration ; and finally, it is advisable that the hydrogen 

 channel should be slightly longer than the other, so as always 

 to turn on the hydrogen in advance, and leave it on a little 

 later, and this may not have been attended to. A penknife of 

 good steel will cut or scrape away a channel easily, and a 

 suitable file will do the rest. 



All taps are best lubricated with a thin smear of animal 

 fat or oil, except those used with ether vapour. The connec- 

 tions between dissolver and jets should always be made with 

 the best rubber tube, and all should be left in situ, and not 

 disconnected except when cleaning or greasing becomes 

 necessary. Care must be taken to grease sparingly, or the 

 grease may clog the passages. 



In all cases where a dissolving -tap is used, the tubes from 

 bag or bottle, or pair of such, are attached to the supply- 

 nozzles of the dissolver, the jet-taps turned off, and the 

 supply to the dissolver turned on. Then turning the dissolver 

 on to each jet in turn, that jet is adjusted separately as to 

 its position, and the gas-supply regulated by the tap or taps 

 on the jet itself. Any future re-adjustment is also made by 

 the taps of the jet concerned. 



59. The Bi-unial Lantern. This is the usual and favourite 

 exhibitor's lantern, more of this pattern being used than of 

 any other. Fig. 62 represents the usual model, fitted with 

 the optical fronts recommended on page 33. Generally the 

 two lanterns are made really in one, as here shown ; but it 



