Screw the magnifier you intend to use to the end C of the body, place the slider-holder P in the hole n, and the ivory slider K with the object, between the plates h i of the slider-holder; set the upper edge of the bar D E to coincide with the division which corresponds to the magnifier you have in use, and tighten it by the milled nut O; now reflect a proper quantity of light upon the object, by means of the concave mirror G, and regulate the body exactly to the eye and the focus of the glasses by the adjusting screw c g, at the same time you are viewing the object.
To view opake objects, take away the slider-holder P, and place the object on a flat glass u, under the center of the body, or on one end of the jointed nippers o. Then screw the silver concave speculum to the end of the cylinder L, and slide this cylinder on the lower part of the body, so that the upper edge thereof may coincide with the line which has the same mark with the magnifier that is then used; reflect the light from the concave mirror G to the silver speculum, from which it will be again reflected on the object. The glasses are to be adjusted to their focal distance as before directed.
THE DESCRIPTION AND USE OF JONES’S IMPROVED COMPOUND OR DOUBLE MICROSCOPES, REPRESENTED IN Fig. 1 AND 2. [Plate IV.] BY THE EDITOR.
The chief imperfections of Cuff’s microscope, as well as of others formerly made, are, their construction rendering them only compound microscopes, the body of the instrument having but a fixed position over the object, and the smallness of the field of view by the old construction of the glasses in the body. To obviate these defects, as well as for the application of material improvements, the late Messrs. Martin and Adams, and the present Messrs. W. and S. Jones, have constructed this kind of microscope in various ways. Two microscopes by the latter artists, which I am now going to describe, appear to me to be the best of any hitherto invented.
Fig. 1 is a representation of the second best sort of compound microscopes. The improvements, though few in number, are essential to the use thereof. The field of view is considerably larger than in the former microscope. The stage and the mirrors are both moveable, so that their respective distances may be easily varied. The magnifiers may be moved about over the object. There is also a condensing glass, for increasing the density of the light, when it is reflected by the mirror from a candle or lamp. It is furnished with two mirrors, one plane and the other concave, and may likewise be used as a complete single microscope.
A B, Fig. 1. represents the body of the microscope, containing a double eye glass, and a body glass; it is here shewn as screwed to the arm C D, from whence it may be occasionally removed, either for the convenience of packing, or when the instrument is to be used as a single microscope.
The eye glasses and the body glasses are contained in a tube which fits into the exterior tube A B; by pulling out a little this tube, when the microscope is in use, the magnifying power of each lens is increased.
The body A B of the microscope is supported by the arm C D; this arm is moveable in a square socket cut in the head that is connected to the main pillar E F, which is screwed firmly to the mahogany pedestal G H; there is a drawer to this pedestal, which holds the apparatus. This arm may be slid backwards and forwards in its socket, carrying the magnifiers and the body of glasses, and also turned horizontally quite round upon the pillar, giving a general motion all over the object on the stage below; which is a material improvement and advantage of this microscope over a similar one described in the former edition of this work, as any unavoidable motion of the living object to be viewed may be followed, by the observer’s hand moving the arm C D as the object changes its place.
N I S is the plate or stage which carries the slider-holder K, this stage is moved up or down the pillar E F, by turning the milled nut M; this nut is fixed to a pinion, that works in a toothed rack cut on one side of the pillar. By means of this pinion the stage may be gradually raised or depressed, and the object adjusted to the focus of the different lenses.
K is the slider-holder, which fits into a hole that is in the middle of the stage N I S; it is used to confine and guide either the motion of the sliders which contain the objects, or the glass tubes that are designed to confine small fishes, for viewing the circulation of the blood. The sliders and tubes are to be passed between the two upper plates.