412 PROCEEDINGS OF THE SOCIETY. 



compound instrument provided with an objective for forming an image 

 of the object and an ocular for viewing the image so formed. 



2. Culpeper's Compound Microscope. Date, before 1738. (R.M.S. 

 Cat. No. 9.) Type — Compound, uncorrected. A modification of Wilson's 

 simple Microscope. A body-tube of ivory, with draw-tube, is provided 

 for the purpose of transforming it into a compound instrument which is 

 mounted on a pillar with a ball-and-socket joint. 



3. CuLPEPER AND ScARLET. Invented about 1738. (R.M.S. Cat. 

 No. 7.) Type — Compound, uncorrected. This tripod form of Micro- 

 scope stand, mounted on a wooden box, was a favourite model for more 

 than a century. It was copied and made by successive opticians with 

 many variations in form, material, and finish until about the middle of 

 last century. There is no fine-adjustment. The object-glass is a single 

 biconvex lens, and the eye-piece has two lenses. 



4. Nathaniel Adams. About 1740. (R.M.S. Cat. No. 152.) Type 

 — Compound, uncorrected. This is of the Culpeper and Scarlet pattern, 

 and is rendered even more unhandy than its original by the addition of 

 a fourth pillar in the space surrounding the stage. This inconvenience 

 was incurred, no doubt, for the sake of the greater rigidity — a distinct 

 advantage in focussing the instrument. 



5. DOLLOND. About 1810. (R.M.S. Cat. No. 121.) Type— Com- 

 pound, uncorrected. This again is of the Culpeper and Scarlet pattern, 

 but shows a great advance in its mechanism, being made all in brass and 

 fitted with a rack-and-piuion focussing arrangement. This specimen is 

 remarkable for its date as showing the persistence and continued improve- 

 ment of an obsolete type of instrument. Described in the Journ. R.M.S., 

 1901, p. 227. 



6. John Cuff's Compound Microscope. Invented about 1744. 

 (R.M.S. Cat. No. 127.) Type— Alternatively Simple or Compound, 

 uncorrected. 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. 



7. Benjamin Martin. 1760. (R.M.S. Cat. No. 52.)" Type— Alter- 

 natively Simple or Compound, uncorrected. For the first time there is 

 a slow and fine movement for focussing, by rack-and-pinion and l)y screw, 

 both applied to the stage, with the constant action of a spring to check 

 the motion. A small compass-joint at the top of the pillar allows the 

 carrying-ring to be turned out of the way when the instrument is used 

 as a simple Microscope. 



8. Benjamin Martin. 1771. (R.M.S. Cat. No. 5.) Type— Alter- 

 natively Simple or Compound, uncorrected. This exceedingly elaborate 

 instrument, of exquisite workmanship, with every conceivable movement, 

 is said to have been made for King George III. Its authentic descrip- 

 tion is " Benjamin Martin's Large Universal Microscope." The triangular 

 upright stem has a compass-joint at its base, and is fixed to an elaborate 

 foot, over which it is adapted to rotate. The stage has micrometric 

 movements in three directions ; it moves the object over a wire scale in 

 the eye-piece. This method of micrometry was invented by Benjamin 

 Martin. The double mirror, as well as the stage, can be raised and 



