LUCEIINAL MICROSCOPE, is an opti cal instrument invented by Mr. Adams. It consists of a hollow pyramidal box, at the smaller extremity of which is a tube carrying the usual system of lenses for magnifying objects. At the larger cud, which is towards the observer, there are two lenses in frames, their axes, as well as those of the small lenses at the opposite extremity, being coincident with time axis of the box ; and between the exterior of the two lenses and the eye of the observer there is usually placed a plate of glass, rongh-ground on one side, which serves as a screen to receive the rays of light pro ceeding from the object whose representation is to be viewed. The object is fixed in a small frame, as usual, and is placed in a groove made for the purpose immediately beyond the tube containing the system of lenses at the small end of the box. Instead of the plate of ground glass, a board painted white is fre quently placed, to serve as a screen, at the distance of 0 or 8 feet from the instrument. Such a screen should have the form of a seg ment of a hollow sphere, the light being re ceived on its concave surface. An Argand lamp, or an oxy-hydrogen light, is placed be yond the object. The light, after passing through a hemisphere of glass, is, when an opaque object is to be viewed, made to fall in a convergent state upon a small concave mirror, which is so inclined as to reflect the light back upon the object; and from the different points on the surface of the latter the pencils of rays proceed through the object-lenses and the box to the glass screen.
By the refraction of the light in passing through the lenses a highly magnified image of the object is formed; and several persons may then place themselves so as to see the image on the screen at the same time ; or, by placing the eye at the small aperture in the produced axis of the instrument, one person may, with a pencil, draw on the glass, or on tracing-paper laid over it, the figure of the ob ject, it being understood that the instrument is used by night or in a darkened room.
When the object to be viewed is transparent, the light is made to fall in a condensed state upon it, after having been transmitted through a convex lens, or two such; and from the object the rays proceed as before to the screen through the system of lenses which consti tute the compound object-glass of the micro scope, and through those at the opposite ex tremity of the box.