78 Microscopical Essays, 



Some tranfparent objects appear to the greateft advantage when 

 the lens at 9 and 10 is taken away; as, by giving too great a 

 quantity of light, it renders the edges lefs {harp, 



The variety of views which may be taken of every object, by 

 means of the improved lucernal microfcope, will be found to be 

 of great ufe to an accurate obferver : it will give him an oppor- 

 tunity of correcting or confirming his difcoveries, and invefti- 

 gating thofe parts in one mode, which are invifible in another. 



to throw the image of transparent objects on a 

 Screen, as in the Solar Microscope. 



It has been long a microfcopical defideratum, to have an in- 

 flrument by which the image of tranfparent objects might be 

 thrown on a fcreen, as in the common folar microfcope ; and 

 this not only becaufe the fun is fo uncertain in this climate, and 

 the ufe of the folar microfcope requires confinement in the fined: 

 part of the day, when time feldom hangs heavy on the mind, but 

 as it alfo affords an increafe of pleafure, by difplaying it's wonders 

 to feveral perfons at the fame inftant, without the leaft fatigue to 

 the eye. 



This purpofe is now effectually anfwered, by affixing the tranf- 

 parent 11 age of the lucernal to a lanthorn, with one of Argand's 

 lamps. — The lamp is placed within the lanthorn, and the end 9, 

 10 of the tranfparent ftage is fcrewed into a female fcrew, which 

 is rivetted in the Aiding part of the front of the lanthorn ; the 

 magnifying lenfes are to be fcrewed into the hole reprefented at 

 12; they are adjufted by turning the milled nut. The quantity 



