Six large ivory sliders, with transparent objects placed between two plates of talc, and confined by brass rings, and six small ditto with ditto. Fig. 10. The larger ones usually contain a set of Custance’s fine vegetable cuttings.
Fourteen wood sliders, containing on each four opake objects, and two spare sliders for occasional objects; all fitted to the cheeks kl of the stage. Fig. 11.
Some capillary tubes, Fig. 12, to receive small fish, and for viewing small animalcula. They are to be placed between the two plates of the stage No. 7, Fig. 4.
A small ivory double box, containing spare plates of talc and brass rings, for replacing any in the small ivory sliders, when necessary.
A single lens mounted in a tortoiseshell case, to examine minute objects previous to their being applied to the sliders.
Opake objects are easily put on the spare sliders by a wetted wafer; and, for good security, gum water may be added.
For the prices of the lucernal, as well as all the other sorts of microscopes, see the [list] annexed to these Essays.
A DESCRIPTION OF THE SEVERAL IMPROVEMENTS MADE UPON MR. ADAMS’S LUCERNAL MICROSCOPE. BY THE EDITOR.
The lucernal microscope being unquestionably the only instrument for exhibiting all sorts of opake objects under a brilliant and magnified appearance, was, as formerly constructed by the late Mr. G. Adams, attended with some inconveniences and imperfections. Upon a proper inquiry into various improvements, and from some observations made by myself, I can recommend, as a complete instrument, one with the following emendations, being, in my opinion, the best of any hitherto made known.
The lucernal microscope, when placed up for use, as represented in Fig. 1. [Plate III.] is of some considerable length. When the eye at L is viewing the image of the object upon the glasses, the objects themselves in the sliders placed at kl at the stage, are without the reach of the hand; so that the indispensible change of the parts of an object, or of one object to another, can only be obtained by the observer’s moving himself from the object to the eye-piece, and vice versa. This adjustment, therefore, proves uncertain and troublesome. The application of rack-work motion to the stage has been contrived and applied to the lucernal microscope by Mr. W. Jones, of Holborn, accompanied with Hooke’s joint and handle, and a lever rod; so that, without altering his position, the observer may change both the horizontal and vertical position of the sliders, and thereby readily investigate all the variety of the objects, and their parts, and with the same exactness as by other microscopes.