414 PROCEEDINGS OF THE SOCIETY. 



systeinaticallv applied the method of "springing" in the movements to 

 prevent loose action. Described in Journ. R.M.S., 1901, p. 728. 



14. Hugh Powell's Large Microscope. 1841. (R.M.S. Cat. 

 No. 2.) Type — Compound : Achromatic. This Microscope is one of 

 three which the Council of the Microscopical Society of London,* soon 

 after its formation, ordered of the three best makers of the day — Hugh 

 Powell, James Smith, and Andrew Ross. The too elaborate and sub- 

 stantial stand was considered the best of its day, and embodies all the 

 most refined movements and apparatus the maker was able to devise. 

 The body is moved by rack-and-pinion. and is attached to a hollow 

 triangular bar. The fine-adjustment actuates the stage. Originally 

 this was a monocular Microscope, but the binocular body with Wenham's 

 prism was fitted to it after the invention of the latter in 1868. 



15. James Smith. 1841. (R.M.S Cat. No. 1.) Type— Compound : 

 Achromatic. This stand was made in execution of an order given by 

 the Council of the Microscopical Society of London in August 1840, 

 and has become a model on which many English stands have since been 

 made. A substantial pillar mounted on a solid tripod supports a 

 grooved limb, which itself carries directly the body, stage, and mirror. 

 Coarse-adjustment is effected by rack-and-pinion moving the body, 

 whilst fine-adjustment for the first time by lever and screw acts on the 

 nose-piece only. The mechanical stage has rectangular motion and can 

 be rotated. Described and figured in Microscopic Journal, ii. p. 1. 



16. Andrew Ross. 1842-3. (R.M.S. Cat. No. 47.) Type- 

 Compound : Achromatic. In execution of an order by the Council of 

 the Microscopical Society of London in 1841, Andrew Ross produced 

 this type of Microscope. The pillar is mounted on a circular base, 

 which rotates so as to increase the steadiness of the base when the 

 Microscope is inclined. The body slides in the grooved hmb, and the 

 fine-adjustment acts by a lever on the nose-piece. The mechanical stage 

 has rectangular movements and also I'otates. Described and figured in 

 Journ. R.M.S., 1899, p. 214. 



17. Dr. Bdavin Quekett's Microscope. 1844. (R.M.S. Cat. No. 3.) 

 Type — Compound : Achromatic. This instrument was designed and 

 mainly constructed by Dr. Quekett, the founder of the Royal Micro- 

 scopical Society, and was bequeathed by him to the Society. Whilst 

 following James Smith's Microscope in general arrangement, this model 

 is characterized by greater rigidity of the foot and pillar. The 

 mechanical stage is made on A. Ross's pattern. Below the stage there is 

 a focussing condenser. 



18. Powell and Lealand. 1848. (R.M.S. Cat. No. 129.) Type 

 — Compound : Achromatic. This model is the first example in which 

 the Microscope is hanging in a tripod, and also the first example in 

 which the fine-adjustment moves the nose-piece by means of a lever 

 within a bar. The mechanical stage has Turrell's rectangular movement, 

 and possesses a focussing condenser. This type of Microscope appears to 

 have been first made in 1843. Described in Journ. R.M.S., 1901, p. 727. 



19. Microscope by Cary, with Varley's Lever-Stage. About 

 1850 (.?). (R.M.S. Cat. No. 134.) An instrument constructed by 



* Now the Royal Microscopical Society. 



