DESCRIPTION OF THE ACHROMATIC MICROSCOPE. 87. 



Goring's engiscope, described in Chap. VIII., being on a 

 much larger scale than that treated of in the present 

 one, is adapted for carrying the shallowest magnifiers 

 which can be required. 



As these instruments have now become the standards 

 by which all the better kinds are made, modified more 

 or less so as to conform to the different views of the 

 artists who make them, I have judged it advisable to 

 treat of their several parts in detail j in doing which 

 many of the remarks I shall have occasion to make, will 

 be found to have a general application. My own instru- 

 ment, with its various modifications and additions, to- 

 gether with their uses, will form the subject of this 

 chapter. In Chap. VIII. I shall give a mere explana- 

 tion of Dr. Goring's aplanatic engiscope ; the method 

 of making observations with, and managing it, being 

 penned by himself in the chapter following it. 



The simplest modification of my achromatic micro- 

 scope is represented at page 82, fig. 11. This can be 

 used only in a vertical position ; but it is admitted, I be- 

 lieve, to be superior to any instrument of that kind, in 

 steadiness, simplicity, and range of powers. It will be 

 readily conceived, that when the circular foot is un- 

 screwed, and the stem c, fitted into a jointed stand, it 

 becomes the second modification, shewn in the following 

 engraving, fig. 12. 



This microscope is represented with its stem and axis 

 in an inclined position, which is commonly the most 

 convenient one for the observer. Those parts of it which 



