I. MICROSCOPES. 903 



3529h. Single Microscope, by Lindsay, 1742. 



The Royal Microscopical Society. 



3529i. Large Solar Microscope, complete. 



The Royal Microscopical Society. 



3529J. Single Microscope, in silver, by Culpepper. 



The Royal Microscopical Society. 



3531a. The Martin Microscope. 



The Royal Microscopical Society. 



Said to have been made by the celebrated Benjamin Martin for Geo. III. It 

 bears no date, but was probably constructed about 1770. For full description 

 see " Williams, On the Martin Microscope," " Transactions of the Microscopical 

 Society," vol. x., 2nd series. It has a triple eyepiece, the middle glass being 

 almost a bull's eye, and insuring a very large field ; the distance between the 

 two upper glasses and the lower one can be adjusted by a rack and pinion 

 varying the power. The original objectives range from 4 inches to -j^th 

 focal length. Higher powers appear to have been added up to ^th ; and there 

 are four high powers up to ^ to be used without the compound body on a 

 small arm which is provided. 



It was supplied with an extensive collection of ancillary apparatus, only part 

 of which is in the possession of the Royal Microscopical Society, by whom it 

 was purchased at a sale of Professor Quekett's instruments. 



It is remarkable for the variety of its adjustments, general beauty of work- 

 manship, and for special contrivances for various objects of unusually large 

 dimensions. There are, however, obvious faults of construction, interfering 

 both with convenience and steadiness. Its highest optical powers do not 

 produce a good definition of such an object as the scales of Podura easily 

 displayed by very much lower modern achromatics. 



3531b. Amician Reflecting Engiscope. 



The Royal Microscopical Society. 



This is fully described by Dr. Goring in " Micrographia," 1837. The 

 principle is due to Amici ; this particular form to Dr. Goring and Mr. Cuth- 

 bert, by whom it was made. The body of the instrument acts as an eye- 

 piece. The narrow tube resembles a Gregorian, reflector. A small inclined 

 mirror receives the image of the object and transmits it to a larger one, which 

 forms a magnified image viewed by the eyepiece. The various arrangements 

 for different adjustments are well contrived, and the workmanship of con- 

 siderable merit. Had not achromatic objectives been constructed, the reflect- 

 ing engiscope "would probably have maintained its ground. 



3518. Old-fashioned Simple, Compound, and Solar 

 Microscope combined ; date about 1800. 



Essex and Chelmsford Museum, Chelmsford. 



Very perfect specimen of old-fashioned simple, compound, and solar micro- 

 scope combined ; presented to the Essex and Chelmsford Museum by the late 

 J. Disney, Esq., E.R.S., about 50 years ago, believed to have been then old, 

 and to have cost originally 40/. 



This specimen affords a good example of the progress of mechanical con- 

 struction. The movement for shading the mirror is so completely super- 

 seded as to be a novelty. 



