One of the most important microscopes ever designed was the large bar limb model by Andrew Ross in the middle of the 19^th century.  Ross reached a pinnacle of design in both the stand and objectives that has rarely been equaled, even today.  The microscope is quite large, standing 19” when closed.  It is also quite heavy on a substantial base.  This model is signed, “A. Ross, London, No. 479,” on the base.  Three of the objectives are original, signed and dated by Ross in 1852.  They feature covered/uncovered correction collar adjustment and come with their original signed canisters.  These lenses include a 1”, ¼”, and 1/8”.   The fully mechanical stage has a rotating slide holder with supports for a multitude of accessories.  The condenser is a Gillett illuminator with its conical ring of minute aperture stops that rotate into place beneath the condenser lens.  It is signed, “Made by A. Ross, London, Registered July 20^th, 1849.”  The bottom of the condenser assembly also accepts a more traditional wheel of stops.  The 3” diameter plano-concave mirror is in excellent condition on both sides with only the slightest age wear.   An additional seven lenses accompany the set, for a total of ten -- a 1/5” Smith & Beck correction collar objective, a 3” Edward Smith, and the rest unmarked objectives that appear to be by Crouch and Swift.  The microscope is pre-RMS thread standard, and has its own unique lens thread.   All the lenses are threaded to fit the microscope, while the Ross objectives have an interior thread and fit with an interior thread adapter that is included with the accessories.  Focus is rack and pinion with a thumb screw micrometer knob for fine focus.    The microscope is finished in lacquered brass with complete coverage showing typical signs of wear.  The case is hand-dovetailed mahogany with side carry handles in brass and a brass escutcheon plate on top.  The case is large, measuring 20 ½” tall by 12” wide and 10 ¾” deep.  It has six accessory drawers.  Two are for slides – one of these has nineteen slides, some signed by Topping, Suter, and Murphy.  There are numerous eyepieces including an eyepiece adapter that accepts the smaller Continental standard size.  Other accessories include two fish plates, condensers (both stage and standing), several lieberkuhn reflectors, stage forceps, brass tweezers, different brass slide attachments, nicol prism condenser and eyepiece, camera lucida eyepiece, and interior thread adapter.  The microscope and case are in excellent condition, noting the following: one of the adjusting screws on the condenser has stripped threads, and a number has been hand engraved into the base above the name (see photo).  The condenser works by hand, nonetheless.  A similar microscope is featured on page 71 of Turner’s book, “Collecting Microscopes.”   This instrument is in fine, working order – extremely rare for its type and condition.  It is an excellent example of one of the finest and most important microscopes ever made.

Item 1428