What did our Forefathers see in a Microscope ? 433 



All will probably endorse the opinion of the learned Dr. Robin- 

 son, of Armagh, concerning the non-achromatic projection Micro- 

 scope — viz. that it was " generally so indistinct that it is fit only 

 for amusing ladies." He, however, suggested a great improvement 

 by the employment of a four-lens terrestrial telescope eye-piece 

 as the projecting lens. 



It is difficult to understand why such an excellent Microscope 

 as that of Dr. Smith's did not become more popular; the cause 

 may be traced in part to Dr. Lieberkiihn's illuminator. The idea 

 in those days was to provide the public with a Reflecting, Aquatic 

 and Opaque Microscope. These terms mean : Illuminated by a 

 mirror ; body capable of traversing the stage ; supplied with a 

 Lieberkuhn. Now Dr. Smith's Microscope was none of these ; it 

 could only be used for the examination of transparent objects. 

 Dr. Lieberkiihn's opaque Microscope took the then small micro- 

 soopical world by storm, and continued to be very popular until 

 Dr. Smith's excellent Microscope had been forgotten. There was, 

 too, another reason why it did not come into more general use ; it 

 possessed a large aperture, which required the mirrors to be very 

 accurately worked and mounted ; therefore, if the instrument had 

 to compete in price with roughly made contemporary Microscopes, 

 the seller's profits would have to be considerably reduced. An 

 examination of old Microscopes shows the optical and mechanical 

 work to be of the roughest kind ; in many instances the lenses 

 have only been imperfectly polished, and they are mounted in 

 roughly turned out cells, fitted with badly cut screws. The profits 

 made on the sale of those instruments must have been very high. 

 So long as the opticians could easily obtain these returns they were 

 not anxious to introduce a Microscope that would not only require 

 more skilful workmanship, but when done would emphasize the 

 rottenness of the image in the ordinary non-achromatic compound 

 Microscope which they were selling with so large a profit ; so they, 

 in their worldly wisdom, agreed to let sleeping dogs lie. 



A number of Dr. Smith's Microscopes were made {circa 1772) 

 by Sir W. Herschel at Bath ; Sir D. Brewster,* in 1837, states that 

 lie has one of them, and gives the measurements of its parts, which 

 differ very much from any of the formulae given by Dr. Smith ; he 

 leaves out, however, the focus of the convex mirror, which omission 

 renders all the other data simply useless ; but the focus of the con- 

 cave mirror was more than twice as great as any of Dr. Smith's. 

 Brewster says that " it performs wonderfully well, though both of 

 the specula have their polish considerably injured ; it shows lines 

 on some of the test objects with very considerable sharpness." Cod- 

 dington.f in 1830, says that he had never seen one of Smith's 



* Ency. Brit., art. Microscope. 



| Coddington's Optics, pt. 2, p. 6G (footnote). 



Aug. 17th, 1910 2 G 



