Vision and Definition under the. Microscope. 1(57 



back of tlie pillar, and raising or lowering the stern to the reijuired 

 position, which is shown by index nnmbers on the octagonal 

 pillar ; the screw is then tiglitened up, and an object mounted on 

 a slide placed on the stage will be in focus. The fine-adjustment 

 is actuated by the milled head of a micrometer screw at the base 

 of the pillar. 



Though not inclinable and very light it shows important 

 improvements over the Microscope of the period, and its work- 

 mansliip is excellent in every detail. (For description and figures 

 see Journ. E.M.S., 1909, p. G33-6.) 



This instrument gives a notably large amount of colour in 

 the imatre. 



Class III. — Compound and Simple Microscopes 



Combined. 



10. John Cuff's "New Constructed Double Microscope" 



(c. 1744). 



The inventor of this model made a distinct improvement in 

 the mechanical construction of the Microscope, and it forms an 

 important link in the evolution of the instrument. The stand is 

 firmer and more rigid, and altogether more handy, whilst the stage 

 is more accessible ; the fine-adjustment applied to the body has 

 greater delicacy. Cuff added the Lieberkuhn to the compound 

 Microscope, fitting it in such a manner that it could be used with 

 all the objectives, and his method was to all intents the same as 

 that employed to the present day. 



Described by Baker, " Employment for the Microscope," 1753, 

 pp. 442-6. (See Journ. E.M.S., 1904, p. 727 ; and 1909, p. 655.) 



11. John Cuff's Single Aquatic Microscope (c. 1750). 

 {Lent hy Mr. Thomas H. Court.) 



Compared with its predecessors the present instrument shows 

 distinct improvements. The following points may be noted : — 

 1. It is provided with a tine-adjustment which focuses the lens, 

 not the stage. 2. The instrument is inclinable. 3. The pillar is 

 mounted eccentrically on its oval base-plate, and is capable of 

 rotation, which gives the Microscope greater stability when used 

 in an upright position. 4. It can be folded for portability. This 

 model is interesting as being the original form of aquatic Micro- 

 scope as first made by Cuff. At the suggestion of John Ellis, F.K.S., 

 it was altered to form what is now known as the Ellis Aquatic 

 Microscope, and in this form it was used by him in 1752, whilst 

 he was writing his work on the Corallines, published in 1755. 



N 2 



