ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



615 



and last, but by no means least, a very powerful Microscope. We are 

 not aware of any other knife manufactured whicli contains a Micro- 

 scope of any description, and we anticipate an enormous demand in 

 consequence. An ordinary pocket bandkercbief submitted to tbe 



Fig. 99. 



lens of this powerful glass, the texture appears nearly as coarse as a 

 sack. Scientific students and merchants will find this invaluable to 

 them, as the knife is of convenient size to be carried in the waistcoat 

 pocket." 



Ward's Eye-shade.* — Dr. E. H. Ward's device consists (fig. 100) 

 of a circular disk of hard rubber or blackened metal, about 1^ in. in 

 diameter, an extension of which in the form of a band 1/2 in. wide 

 crosses in front of the nose of the observer, but quite out of the way, 

 and encircles the top of the 



draw-tube or compound body Fig. 100. 



just below the ocular. As now 

 used, this shade is made of hard 

 rubber, which is of light weight, 

 and suitably dark colour, is 

 less likely than metal to 

 scratch the brasswork with 

 which it comes in contact, and 

 is so elastic as to be applicable to a considerable variety of tubes. 

 The same shade, for instance, can be used on tubes of from 1 to 1^ iu., 

 or from 1/8 to 1|, the best fit being of a size midway between the two 

 extremes. Besides this easy range of adaptation, this eye-shade diflers 

 from those hitherto in us'; in its attachment to the body instead of 

 the ocular, by wliicli it is brought to an advantageous distance from 

 the face, and is retained in position as long as the instrument is iu 

 use, instead of being removed with the ocular and requiring a fresh 

 application every time that is changed. It is reversible by 6imi)ly 

 turning it over, and can thus be instantly transferred from the left 



♦ Arn.,r. Mon. Micr. .Joiirn., v. (1884) pp. 82-3 (1 fif,'.). 



