ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 657 



SHUTTLEWORTH. 1786. 

 Type — Alternatively Simple or Compound, uncorrected. 



The stand of this instrument is a somewhat later imitation of the 

 Benjamin Martin type. The triangular stem has a compass-joint at 

 its base, by means of which the whole Microscope is inclinable. The 

 stage has rack-and-pinion focusing movement. The body is fixed to a 

 movable and rotating arm, and carries Francois Watkins' rotating 

 multiple lens-carrier nose-piece. The mirror and condensing lens slide 

 on the triangular pillar. 



Described and figured in Journ. R.M.S., 1908, p. 3(55. 



JONES. 1798. 

 Type — Alternatively Simple or Compound, uncorrected. 



This model follows an earlier form of Francois Watkins, inasmuch as 

 the compass-joint making the Microscope inclinable is raised to the top 

 of an upright stem, fixed to a tripod folding foot. To the joint is fixed a 

 square limb on the top of which a short arm, movable by rack-and-pinion, 

 supports the body of the Microscope. The stage moves on the limb by 

 rack-and-pinion, which serves for the focusing of the object. The 

 mirror and condensing-lens slide on the same square limb. The object- 

 glasses are contained in a rotating multiple lens-carrier nose-piece. 



The instrument was described by its makers (W. and S. Jones, of 

 Holborn) as the " most improved " Micrcscope, a description much 

 better justified than superlatives — and especially the superlatives used by 

 salesmen — commonly are, for this instrument does, in fact, represent the 

 culminating point reached by the dioptric instrument before the intro- 

 duction of the achromatic objective. 



Described and figured in Adams' " Essays on the Microscope," 

 2nd ed., 1798, p. 99. 



Class 4. — Reflecting-. 



CUTHBERTS Reflecting Microscope. About 1827. 

 Type — Compound : Catoptric. 



The attempts made at the close of the eighteenth and beginning of the 

 nineteenth centuries to produce achromatic object-glasses for the Micro- 

 scope having failed, owing to technical difficulties, the maker of this 

 Microscope attempted to produce achromatism by means of mirrors, carry- 

 ing into effect a suggestion originally made by Newton which one or 

 two other makers had followed up. Cuthbert's instruments are said by 

 Mavall to have been the best of their type. The magnification of objects 

 is here effected by means of very small reflecting specula, and the result 

 for low and medium powers was very fairly satisfactory. The body is 

 fixed by a compass-joint on the top of the telescopic stem supported on 

 a folding tripod. The focusing is effected by moving the stage, and the 

 latter has rectangular motion. 



Described and figured in Mayall's Cantor Lectures (1885), p. 58. 



