590 



Notes. 



An Early Compound Microscope with a Mirror attached 



to its Limb. 



By Edwaed M. Nelson. 



This old Microscope will on examination be found to possess 

 some points of interest. A very cursory glance at fig. 149 shows 

 that it is home-made by some ingenious amateur. The body is 



composed of three brass tubes sliding 

 into each other. These obviously were 

 not intended for draw-tubes, but merely 

 for the convenience of fixing the lenses 

 in their proper positions. The lenses 

 are held in their place by split wire 

 rings ; the diaphragms are made of 

 cardboard. The lenses are four in 

 number, two of which form a Huygh- 

 enian eye-piece, the third being the 

 back lens of the objective, after the 

 plan introduced by Benj. Martin. 



The limb is merely an iron rod, 

 attached to a heavy circular foot. The 

 stage is elementary in the extreme : it 

 has a socket to hold the stage forceps, 

 but a slip can be laid across the bars 

 when they are bent round. The ob- 

 jective merely pushes on to the nose- 

 piece without any screw. 



The ball and socket for the mirror 

 is of a very simple and ingenious con- 

 struction, and it will be noted that the 

 mirror is attached to the limb. This is 

 an important point, for it took some 

 years to arrive at the obvious improve- 

 ment of attaching the mirror to the limb. 

 The mirror was first applied to the Microscope by Hertel in 

 1715, but then, as also in the Culpeper and Scarlet (1738), and 

 John Cuff (1744), the mirror was attached to the box -foot. We 

 first meet with a mirror attached to the limb in a simple Micro- 

 scope, viz. that of Lindsay* (Invented 1728, Patented 1743); a 

 signed, dated (1742), and numbered (No. 22) example being in our 

 cabinet. The next instance where we find it is in Ellis's Aquatic 

 Microscope,f 1755 ; but the example before you is probably the 



* Journ. K.M.S., 1895, pi. 4, p. 257. 



t Figured in many books besides Mr. Ellis's work on History of Corallines.; 

 probably the most accessible is Adams on the Microscope, 1798, pi. 7 B. 



Fig. 149. 



