158 



SCIOPTICON MANUAL. 



unsound place in the lime, it sometimes produces a his- 

 sing sound. Moving the lime or varying the pressure 

 will, in most cases, abate the annoyance. 



MARCT'S TRIPLE JET. 



In this apparatus, the three burners already described 

 are interchangeable. 



Fig. 40. 



Fig. 40 represents the house gas-burner in position, 

 while Nos. 1 and 3 are in the cells d and e, to be shut in 

 by the cover/. The broach in the cell v is in proper 



