WITH THE MICROSCOPE. -79 



bottles must be sent to the manufacturer to be filled, as the gases 

 are forced into them by a costly pump requiring special arrangements. 

 Mr. Highley, who has given particular attention to the improvement 

 of the magic lantern and all its appliances, has quite recently under- 

 taken the production of these " condensed gas bottles," and the 

 supply of oxygen and hydrogen gas. They are made of wrought iron 

 fitted with lever valves of very careful construction, and are tested to 

 withstand more than double the pressure they will ever be subjected 

 to in practice. He finds that it reduces both the bulk and the cost 

 of the oxy-hydrogen apparatus very materially. It promises to make 

 a most convenient and efficient arrangement for the lecturer, and 

 may also be used for projecting a powerful beam of light into the 

 cavities of the human body as for laryngoscopic examinations, <S:c. 

 See Mr. Highley's paper read before the Society of Arts, January 

 4th, 1863. Mr. How, of Foster-lane, also makes the requisite 

 instruments and apparatus. 



A list of books on photography of value to the practical operator 

 will be found at the end of the present volume. 



