HAND AND OTHER APPARATUS. 



43 



microscope, and blacken it inside. In the opposite 

 end fix a piano convex lens about three inches focus, 

 its convex side being turned towards the eye-piece, 

 or preferably a universal screw to receive an ob- 

 jective of about the same power. Make another tube 

 six or seven inches long to fit over the first and the 

 focussing glass is completed. 



The end of the outer tube being placed against 

 the screen, its roughened side is brought into focus 

 by sliding the inner tube within the outer. When the 

 best focus has been obtained, which may be done by 

 fastening a very small fly or other minute object on 

 the focussing screen, the inner tube is marked with 

 a circle where it joins the outer, thus enabling it to 

 be placed in the same position when again required. 



The third difficulty, namely, want of light, cannot 

 be overcome, as any increase in quantity of the light, 

 decreases the visibility of the structure. 



The stand intended to support the microscope and 

 its accessories requires to be made as firmly as possi- 

 ble. The following is a description of the form 

 finally adapted by the writer after more than ten 

 years' experience, dm'ing which time scarcely a month 

 elapsed without the trial of some fresh device. It is 

 still far from perfect, but we liope, its simplicity 

 will in some degree atone for its numerous defects. 



A beam ten inches wide two inches thick and six 

 feet long, is sawn into three separate portions, three, 

 one, and two feet long respectively. On the upper 

 surface at each side flush with the edges, two laths 

 one inch wide, half an inch thick, and the same 



