loS OPTICAL PROJECTION 



to barely affect even the hydrogen bye-pass name ; else it 

 will snap the jet out. 



The connections of this dissolver are sometimes found 

 rather confusing, but are easily understood with a little 

 thought. Both the channels revolving in the same direction, 

 but on opposite sides of the plug, it will be seen that when 

 hydrogen is turned on to the top left-hand nozzle, oxygen 

 is turned on to the bottom right-hand nozzle. It is easily 

 understood if we remember that the two nozzles are ' on ' 

 which are covered by the lever in either position. This tap does 

 however, involve very long india-rubber tubes between the 



tap and the jets, and on this 

 account I prefer the other form, 

 shown in fig. 61. In this dis- 

 solver each supply nozzle, with 

 its pair of jet nozzles, is on the 

 same side of the plug, but one 

 above the other. Therefore 

 both jet nozzles are on the same 

 side for each jet, and the pair of 



PI&. 6i.-piug Dissolving Tap nozzles are on ' towards which 



the lever is turned. The hydro- 

 gen bye-pass is often provided by cutting a small groove, 

 beyond the supply channel, right round the plug ; but a con- 

 necting tube and stop-cock, as in the ' star ' form, is better. I 

 have my own tap so modified that the jet nozzles project at 

 an angle towards the front, which is an improvement, further 

 shortening the rubber tubes. This dissolver can, if preferred, 

 be affixed sideways to the back of the lantern, so that the 

 nozzles point upwards to the top jet and downwards to the 

 bottom one, and very short rubber tubes then suffice. 



A third form of dissolver consists of two separate three-way 

 taps arranged side by side. 



Dissolvers often want adjusting. The apertures may be 

 too small to supply a good jet, and both these and the channels 



