284 



NOTE. 



An Astronomical Eye-piece used as a Simple Microscope. 



By E. M. Nelson. 



Seveeal Fellows of this Society are also interested in astronomy, 

 and possibly use the beautiful Zeiss orthoscopic eye-pieces in their 

 telescopes ; but they may not be aware that these eye-pieces, when 

 used upside down, i.e. with the eye-lens next the object, make 

 excellent lenses for a simple Microscope, or loup, as it is now 

 called. Finer pictures of a blow-fly's tongue than those seen with 

 12^ and 9 mm. orthoscopic eye-pieces cannot be obtained. The 

 focusing tube, when taken out of my telescope, just happens to fit 

 the 6 -power Zeiss-Steinheil lens-holder of Paul Meyer's dissecting 

 stand. By using the 5 mm. orthoscopic eye-piece as an object- 

 glass, and by placing the 18 mm. orthoscopic eye-piece in the other 

 end for an eye-piece, a compound Microscope of some considerable 

 power is improvised. This will show Grayson's 20,000-band quite 

 easily, and with a little movement of the concave mirror the 

 25,000-band can be readily seen. It will also show the exclama- 

 tion marks on the Podura scale, and it will resolve a coarse Navicula 

 lyra. This is, of course, only a plaything, but these eye-pieces, 

 when used as loups in the manner indicated, give really very 

 fine images. The powers are — 



18 mm. . . Xlo 9 mm. . . x 27 



121 ^^ . . xl9 o „ . . x50 



