no 



Microscopical Essays. 



diftance, and the light be feen reflected from the fpeculum 

 ftrongly upon the object, by which means it will appear very 

 diftincr. and clear. 



Of Ellis's Single or Aquatic Microscope, Plate VII. B. 



This inftrument takes it's name from Mr. John Ellis, author of 

 <f An EfTay towards a Natural Hiflory of Corallines," and of the 

 " Natural Hiflory of many curious and uncommon Zoophytes." 

 This was the inftrument that he made ufe ofj and by which he 

 was enabled to explain many fmgularities in the ceconomy and 

 conftruction of thefe wonderful productions of nature. To the 

 practical botanift this inftrument is recommended, by the 

 refpeclable authority of Mr. Curtis, author of the Flora Londi- 

 nenfis, a work which does credit to the author and the nation. 

 This micro fcope is fimple in it's conftruction, eafy in it's ufe, and 

 very portable ; thefe advantages, as well as fome others which it 

 alfo has over every other portable microfcope, have accelerated 

 the fale thereof, and caufed it to be very much adopted. 



Description of the various Parts of the Microscope. 



K, the box which contains the whole apparatus ; it is gene- 

 rally made of fifh-fkin ; on the top of the box there is a female 

 fcrew, for receiving the fcrew which is at the bottom of the pillar 

 A, a pillar of brafs which is fere wed on the top of the box K. 



D, a brafs pin which fits into the pillar ; on the top of this pin 

 Is a hollow focket to receive the arm which carries the magnifiers ; 



the 



