lad1188-1.jpg (52965 bytes)

lad1188-2.jpg (52905 bytes)

lad1188-3.jpg (57904 bytes)

 

Ladd brass microscope with fusee chain

One of the more innovative microscopes of the 19th century, this large compound instrument by William Ladd features the fusee chain drive that he introduced in 1851. It was felt at the time that the fusee chain drive resulted in a smoother travel of the moving parts. While this was true, the chain was also prone to breakage. Many of the Ladd instruments that survive have broken fusee chains. This particular instrument is unique it that both the coarse focus and the mechanical stage are driven by fusee chains. The microscope is large, standing 19" tall when closed. (See comparison photo.) It is signed in script on the stage, "W. Ladd, 34 Chancery Lane, London." The microscope does not have the RMS lens thread, which would date it prior to, or around 1858. Fine focus control is a nose piece micrometer screw. The stage has full x-y movement, plus a rotating slide tray. The 3" plano-concave mirror show age veining on both sides, but is quite usable. The condenser holder beneath the stage is rack and pinion controlled, and has two centering screws. Three condensers accompany the set: a parabaloid, a darkfield, and a nicol prism polarizer with accompanying analyzer. In addition there is a condenser that accepts screw in stops, but no stops are with the accessories. The optical system includes three Ladd objectives, a 1" and a " – both with brass canisters signed with the Ladd name – and a 1/5" signed Ladd that is adjustable for coverslip size. All lenses have an internal thread and attach to the microscope with an adapter. Two unmarked eyepieces, a stage forceps, and brass tweezers complete the set. The microscope is finished in polished brass with no lacquer. It comes in a hand dove tailed mahogany case with brass carry handle. The case is in fine usable condition. The microscope is an important early example of the fusee chain driven model. Its imposing size and innovative mechanical system render it an impressive and important model in the history of the English microscope.

Item 1188

microscope menu home