728 PKOCEEDINGS OF THE SOCIETY. 



means of a lever inside a bar movement. The screw which moves the 

 lever is placed at the side of the bar. This must have been about the 

 last Microscope made with the side screw, for it was in this year (1848) 

 that the screw was placed vertically above the lever, where it has re- 

 mained ever since (v. Quekett, 1st edition, 1848, p. 80, fig. 45). 



It will be noticed that the lower part of the body where it joins the 

 arm is conical. This is the last remnant of a design which had been 

 in vogue for 100 years. Thus this instrument is dated 1848. Powell's 

 Microscope of 1839 had a more pronounced cone. Messrs. Watson and 

 Sons have most kindly presented an example of this interesting model 

 to the Society to-night. The cone was still more j»*onounced in And. 

 Pritchard's Microscope of 1832 (v. Microscopic Cabinet). The con- 

 tinuity is maintained by the following instruments : — 



C. Gould's pocket Microscope, by Cary, ante 1828 (example pre- 

 sented by Mr. F. Gleadow in our Cabinet). 



Jones' improved 1798 (example presented by Messrs. Watson and 

 Sons in our Cabinet). • 



Adams, 1785 (example presented by Mr. J. M. Offord in our Cabinet). 



Benj. Martin, 1776 (example presented by Dr. Dallinger in our 

 Cabinet). 



Adams, The Variable Microscope designed by a Nobleman, 1771. 



Adams, New Universal Double Microscope, 174 G. In this instru- 

 ment the cone is very pronounced. 



John Cuff, New constructed Double Microscope, slightly conical, 1744. 



The 100 years are therefore more than completed. 



(2) Microscope by Hugh Powell, presented by Messrs. Watson and 

 Sons. 



Date : — This Microscope must have been made prior to 1841, other- 

 wise Mr. Lealand's name would have been coupled to that of Powell, 

 because in that year Mr. Lealand joined the firm. 



Stand : — A flat solid tripod with an upright pillar. The question is, 

 Who was the inventor of the solid tripod '? In old Microscopes the 

 tripod always folded for packing. See Benj. Martin 1776, Adams 1785, 

 Jones 1798, all in our Cabinet. The last of these folding flat tripod 

 feet is figured in Pritchard's Microscopic Illustrations, 1838, illustrating 

 Dr. Goring's Operative Aplanatic Engiscope. In the text (p. 93) 

 Pritchard says, " I have lately made some of his (Dr. Goring's) instru- 

 ments with a solid base, similar to my own, which are decidedly prefer- 

 able." In the South Kensington Museum there is one of these Goring 

 Microscopes mounted on a solid tripod foot. (Powell was the maker of 

 Pritchard's Microscopes.) The upright pillar can be extended, and 

 damped with a pinching collar ; the limb is attached to the pillar by a 

 compass joint ; this attachment is however peculiar, because it permits 

 the body, stage, and mirror, in fact the whole Microscope, to be turned on 

 one side. Microscopes having this kind of movement are figured in 

 Microscopic Illustrations, pp. 88, 92, figs. 12 and 17. The body is held 

 by a solid bar from which it can be unscrewed ; a clamping nut is then 

 loosed at the top and the bar rotated. The other end of the bar, which 

 is made of much lighter metal, has a spring hole in it for the purpose of 



