5.- Microscopio compuesto de Campana, 1665. ITALIA.

Giuseppe Campani Rome Italy. Compound monocular before 1665.
The entire body is of dark wood with a brass stand, and consists of two barrels. The lower, outer barrel has a fine screw adjustmeat on the outside for raising and lowering, and the inner barrel is 2 inches long and has a coarse thread adjustment al the lower t-I%4 inches that provides for adjusting between the objective and the eye lens. There is also a wooden dust cap.
The objective is held in a wooden cell that screws on the now and has a pinhole opening. The maker's mime is incused around the upper ring that is attached to the disc forming the base by three narrow, flat brass pillars.
The slide holder consists of two rollers on opposite aides fixed to the upper side of the base. Below the base is a second disc the same size as the base that has two thin, almost vertical steel springs that press on the roller. The springs arc bent slightly inward, and by pressure on the rollers tend to draw the lower disc up against the base. The use of the second disc suggests the spiral spring arrangement. later devised by Filippo Bonanni, the 17th century Italian microscope maker. The central hole in the base and the lower plate indicates that the instrument was intended for examining trans. parent objects lay holding them to the light.
There is an objective and an eye lens that are made fly a screw ring. Tao absence of a field lens dates the instrument before Hooke (1665) at which time the field lens was claimed as a new improvement. Height is 4-1/2 inches and the base is 1-1/B inches in diameter. John Mayall indicated that this was the just system of screw focusing applied to a microscope of which he was aware. THE BILLINGS MICROSCOPE COLLECTION (AFIP 49001 60-4713-412)