- Giovanni Battista Amici
Horizontal microscope by Amici (the working instrument of Prof. Alexandro) in walnut case which forms stand; 5 eyepieces; 5 o.gs screwed together; 2 lieberkuhns; frogplate; stage forceps; hand forceps; adapter to form simple microscope; memorial handkerchief and original directions by Amici; various glasses &c
This form of microscope, which was exhibited by Amici in Paris in 1827, is of particular interest as being one of Amici's earliest achromatic instruments; it also possesses novel features of design.
The main pillar, which serves as the limb of the instrument and carries the stage and the mirror, is mounted on the box which thus serves as a stand for the instrument. On top of the limb the body tube is fixed in a horizontal position.
The objectives are screwed into a socket on the under side of the body-tube at one end, and immediately above them, mounted inside the tube, there is a right angled prism which reflects the light coming through the objectives into the horizontal tube, at the other end of which is situated the eyepiece.
The stage is provided with rack-and-pinion adjustment on the limb and is moveable in two directions at right angles by micrometer screws acting on two brass plates. The upper of the two plates is directly attached to the stage and the lower carries the mounting for the upper plate. Thus rotation of the drum-head at the side of the limb moves the upper plate, and with it the stage; rotation of the drum-head at the rear of the limb moves the mount carrying the upper plate, and thus also the stage. On each of the graduated drum-heads one division corresponds to approximately 1/8000in.
The powers, which can be screwed together and used in combination, are achromatic doublets. The eyepiece is of the Huygens type with a plano-convex field lens of 3in. focus and a plano-convex eye-lens of 1in. in focus, the distance between the two being about 2 1/4in. Cross wires are mounted about 1in. from the eye-lens.
The concave mirror reflecting light into the instrument is extra large (3 1/4in. diameter) and is adjustable on the limb by rack and pinion.