8 Mr. T. D. Aldous on the 



very little employed; it is, however, interesting from the fact 

 that it is the first compound instrument made for sale in this 

 country ; also as the first appearance of an ordinary condenser 

 such as we now use. After this — in England at least — nothing 

 seems to have been attempted in the direction of improvement 

 to the compound microscope for about thirty years. 



But the year 1738 is historical from the publication of 

 Lieberkuhn's invention of the solar microscope, which the in- 

 ventor himself exhibited before the Eoyal Society in London 

 in 1739 ; this was, in fact, the first projection microscope. 

 Lieberkuhn illuminated his solar microscope by the sun's rays 

 falling directly on a condensing lens, and so its use was limited 

 to a short period of the day. About 1747, however. Cuff greatly 

 improved the apparatus by applying a moveable mirror, thus 

 making it available for general use ; it was principally used for 

 the exhibition of animalculse and the circulation of blood, and 

 was much recommended for drawing purposes, the image being 

 thrown on a thin sheet of paper, the artist standing behind the 

 screen and tracing the outline with pen or pencil. This in- 

 vention, together with the discovery, by Mr. Trembly, of the 

 Plumatella, a fresh-water polype, about this time, and also the 

 observations of Baker and the elder George Adams, gave to 

 microscopical research a tremendous spur. 



In 1740 the cumbrous compound instrument of Marshall was 

 greatly improved and reduced to manageable size by Scarlet and 

 Culpepper, after the latter of whom the instrument was named ; 

 their first microscope had a wooden body, but this seems to have 

 been at once replaced by metal, as in 1742 Baker describes .the 

 instrument as of brass. A specimen of this instrument, singu- 

 larly complete, I am able to show you ; it is probably of rather 

 later date, but not much, as those made in 1771 by the elder 

 Adams have a cross-shaped stage instead of this circular one. 

 The whole is exactly similar to that described by Baker, the 

 only difference being in the scrolled supports, which are illus- 

 trated in his 'Microscope Made Easy' as straight. 



"In 1744," says Baker, "I found, however, some further 

 alterations were necessary to make this instrument of more 

 general use, as 1 fully experienced in 1743, when examining 

 daily the configurations of saline substances. The legs were 

 continual impediments to my turning about the slips of glass ; 

 besides, pulling the body up and down was likewise subject to 

 jerks, which caused a difficulty in fixing it exactly at the focus. 

 There was also no good contrivance for viewing opaque objects." 

 Baker applied to Cuff, the optician, with the result that he pro- 

 duced an instrument supported on a sliding pillar, and fitted 

 with a fine adjustment. 



At this time microscopy seems to have been given another 



