PROJECTIONS. 43 



through the objective above it, and falls upon a 

 second mirror, which is so mounted as to allow re- 

 flection in any direction. The same device is made 

 a part of the standard lantern of the country, and 

 called the " College Lantern" manufactured by George 

 Wale & Co., of Hoboken, N. J. By an ingenious 

 arrangement the change from the horizontal to the 

 vertical can be made in less than half a minute. The 

 microscope, the polariscope, the electric-light regulator, 

 and several other fixtures, are fitted to this instrument, 

 making it a most perfect and complete lantern. 



Such a vertical attachment as is shown in Fig. 25 is 

 applicable to the porte lumiere, but one can be extem- 

 porized, that will do good service, with such material as 

 is accessible to every one. An iron filter-stand, such 



Fig. 27. 



as is in common use in every chemical laboratory, may 

 be taken, and the condensing lens c laid upon the lower 

 or largest ring, and the objective, a, upon the upper or 

 smaller one, as shown in Fig. 27. Below the lower ring 

 a plain mirror m may be placed, at such an inclination 

 that the beam of parallel rays falling upon it from the 



