42 



THE ART OF PROJECTING. 



merits of a horizontal galvanometer needle, etc., such 

 as cannot be exhibited with the common forms of ap- 

 paratus for projections. At first the awkward method 

 was adopted of turning the lantern up so that it rested 

 upon its back. This endangered the condensing lenses 

 of the lantern from the great heat immediately under 

 them. Professor 

 Cook and Doctor 

 Morton have great- 

 ly improved upon 



Fig, 25. Fig, 26. 



this, and have added a most valuable attachment to 

 the lantern. 



The cut (Fig. 25) represents this invention. It con- 

 sists of a plane mirror inclined at an angle of 45°, and 

 when so placed that the beam of light from the lantern 

 falls upon it, it is reflected perpendicularly upwards 

 upon a lens that converges the light when it passes 



