I. MICROSCOPES. 905 



This microscope of Simon Plcessl was used by Prof. F. Cohn in all his 

 researches during the years 1845-1862, and affords a historical proof of the 

 degree of perfection attained by microscope manufacturers 30 years ago, as, at 

 the time it was constructed, it was considered one of the best instruments on 

 the Continent. 



3531c. Goring's Operative Aplanic Engiscope, described 

 and figured in Pritcliard's " Microscopic Illustrations," 1830. 

 An early form of compound microscope mounted with ball and 

 socket universal joint, oval plane mirror and 2 in; condenser 

 beneath the stage, black box for opaque objects, forceps, &c. 



John Spiller. 



8531d. Slit and Prisms used in the first form of Spec- 

 trum Microscope. H. C. Sorb?/. 



As shown by the woodcut exhibited, the slit was placed some distance 

 from the microscope, and the prism fixed below the achromatic condenser, 

 so that an image of the spectrum was seen on the object examined under the 

 microscope, and the relative powers of absorption for different rays observed. 

 This form of apparatus has been entirely abandoned for many years, and 

 replaced by the exhibitor's direct vision spectrum eyepiece, exhibited by 

 Mr. John Browning, and by the exhibitor's binocular spectrum apparatus, 

 exhibited by Messrs. R. & J. Beck. 



This apparatus is described in the exhibitor's paper in the " Quarterly 

 Journal of Science," 1865, vol. ii., p. 198. 



.) MICROSCOPES BY MODEKN MAKERS. 



3532. Microscope ; the first made on Joseph Jackson 

 Lister's model, by James Smith, in 1839, but refused by the trade 

 as being too great a departure from the old and approved model. 



Joseph Beck. 



3532a. Microscope with Large Compound Stand. 

 Designed by Andrew Eoss about 1832. With rotating stage and 

 sub-stage added in 1851. T ^ inch objective of old form attached. 



Ross $ Co. 



3532b. Microscope with Large Compound Stand on the 



Jackson slide principle. Designed by F. H. Wenham in 1873. 

 With inch new patent objective attached. Ross $ Co. 



3532c. Microscope with Portable Folding Stand for 



travellers. Designed by F. H. Wenham in 1874. With 1 inch 

 triple objective attached. Ross fy Co. 



3532d. Microscope with Portable Stand, with objective 

 suitable for students. Ross $ Co. 



3533. Microscope, on the approved Jackson model, with a 

 limb continued under the stage and planed out in one continuous 

 groove to insure perfect concentricity of the optical and illumi- 

 nating apparatus. Designed for and exhibited in the- Great 

 Exhibition of 1851. R. fy J. Reck. 



