STEPHENSON'S SAFETY STAGE. 



8 9 



an ordinary drill lubricated with the same material. Glass 

 may be turned to any shape in the lathe by using a smooth 

 cut file, kept moistened with oil of turpentine, as the turning 

 tool ; but in order that this operation may be successful it 

 is necessary that the piece for turning be not of too large 

 diameter. 



FIG. 78. 



In working with high powers and expensive slides there 

 is often a risk of either one or the other getting damaged, 

 and this is especially the case 

 with immersion objectives, where 

 the kindly help of the dust on 

 the cover-glass is not obtainable. 

 It is never advisable to take high 

 powers or rare slides to conversa- 

 zione or other public meetings, 

 on account of the miscellaneous 

 character of observers ; but if such 

 a proceeding is imperative, the 

 exhibitor should certainly provide 

 himself with one of Stephenson's 

 new safety stages, shown in 

 Figs. 78 and 79, which may be the 

 means of saving him a few regrets. It is so constructed that 

 if by chance the object-glass is racked down on the thin cover, 



FIG. 79. 



