APPENDIX 



ACHROMATIC GAS LAMP. 



Gas, now so generally introduced into our dwellings, presents 

 many advantages over oil and other lamps requiring wicks, on 



account of its cleanliness, 

 being ever ready for imme- 

 diate use, never requiring to 

 be trimmed, and a perfect 

 control of the flame. "When 

 employed in the ordinary 

 way for microscopical inves- 

 tigations, it, however, pre- 

 sents the defect of a glaring 

 yellow flame, the reflected 

 rays from which are exceed- 

 ingly trying and injurious to 

 the eyes, and likewise ren- 

 der the definition obscure. 



To remedy these evils, 

 Mr. S. Highley, junr., of 

 Fleet Street, has construct- 

 ed a lamp of the following 

 description, represented in 

 section by fig. 264: a, the 

 base; b, a socket, carrying 

 the stopcock, by which the 

 flame is regulated; into 

 this screws a stem, c, 4^ 

 inches long, in which slides, through a stuffing-box, an inner 

 tube, d; by this arrangement the stem may fee heightened 

 when it is required to throw the rays on the stage of the 



Fig. 264. 



