DESCRIPTION:
This is a rare example of an early achromatic monocular microscope retailed by the firm of Troughton & Simms, London. It is almost identical to another example retailed by Carpenter & Westley, and may have originated from J.B. Dancer's workshop when he still sold to the trade, either just before or after the dissolution of his partnership with Abraham in 1845.

The instrument is all made in brass and is supported by a Y-shaped foot measuring 15 1/4cm x 16 1/2 cm upon which arises a tapered pillar, at the top end of which is a compass joint connecting it with a Lister limb, and allowing this to be tilted at any required angle. The upper portion of this holds an outer body tube, which is affixed to it by 8 screws. To the lower extension of the limb is affixed a gimbal holding the mirror. An inner body tube, 218 mm long, slides within the outer tube and its coarse adjustment is activated by a rack and pinion recessed within it and operated by a single knurled knob on the right-hand side. The fitting tube diameter for the eye pieces measures 30.7 mm. There is a short lever fine adjustment acting on the nose piece, which carries the 14.5 mm Pritchard objective thread.

The mechanical stage is of the Varley type and is operated by a long lever situated on the left-hand side below the stage. The underside of the stage carries a ring for the insertion of substage accessories. The microscope stands 400 mm high when in use. There is a sliding bar on the upper surface of the stage, the position of which can be adjusted by a sliding rod, for the positioning of slides.

ACCESSORIES:
These include two top hat eye pieces with approximate magnifications of 5X and 8X and two objectives in matching cans engraved 1 inch and 2 inch. Their lids are also engraved Troughton and Simms. The middle drawer contains a live box, stage forceps and a stage micrometer marked Troughton &: Simms London. The present owner has added a replica tommy bar for the tightening of the limb, there being a specific recess for this at the front of the middle drawer.

CASE:
The microscope is contained within a mahogany case measuring 380 x 202 x 175 mm and slides into this side-on. On the left, there are three drawers fitted with attractive recessed handles, the top drawer containing a number of slides, the others holding the accessories.

CONDITION:
The microscope is in excellent condition with most of the original lacquer still present. The lower element of the 2 inch objective has delaminated. When purchased, the mirror was lacking, and a replacement period single sided concave mirror has been fitted albeit of slightly too small a dimension. The mahogany case is of a beautiful patinated color, with only the lock being defective.

HISTORY:
Edward Troughton (1756-1835) worked as an instrument maker with a particular interest in the manufacture of dividing scales. He was known to have made a dividing machine and a pillar-frame sextant, and was awarded FRS in 1810. It is known, that at one stage, he employed Josiah Dancer (1779-1835), the father of John Benjamin Dancer (1812-1887).

In 1826, Troughton formed a partnership with William Simms (1793-1860) who was also concerned with dividing and with telescopes, but neither had a particular interest in microscopes, and so it is most likely, that this microscope was merely retailed by them. During the period 1835-1850 it was commonplace for retailing opticians to obtain microscopes from the "trade", i.e. from makers who were providing unsigned instruments, which were subsequently inscribed with the retailers' name, before passing them on to customers. In the Science Museum collection is an almost identical microscope (save for the blackened foot, lever for stage movements now being on the right-hand side) which is signed by Carpenter & Westley, London. Both feature the characteristic Y-shaped foot, shape of the limb, and coarse focusing arrangement as we find in John Benjamin Dancer's Ca 1848 microscope, and it may also be no coincidence that his father Josiah once worked for Edward Troughton. It therefore seems plausible that this microscope was made by Dancer and merely retailed by Troughton & Simms, while another example was sourced from him by Carpenter & Westley. Certainly, the latter firm is also known to have sold earlier model microscopes made by Abraham & Dancer (1841-1845) and Dancer himself after the dissolution of their partnership. Certainly, this type of coarse focus is also found on an early Ross instrument (Ca 1836-37), and also features in Powell & Lealand's Iron model, but the resemblance to Dancer's microscope appears to be more compelling. Unusually though, the objective thread is identical to that employed by Andrew Pritchard, which may have been specified by the original owner who sought to upgrade his microscope stand, but wished to continue using Pritchard's objectives. Hence perhaps only the presence of 1 and 2 inch objectives of a more modern design?.

REFERENCES

Bracegirdle, B. Notes on modern microscope manufacturers. Quekett Microscopical Club 1996.
Clifton, G. Directory of British Scientific Instrument Makers 1550-1852. Zwemmer. The National Maritime Museum.
Nuttall, R.H. Microscopes from the Frank Collection 1800-1860. A. Frank, Jersey, Channel Islands.
Quekett, J. Practical Treatise on the use of the Microscope. 1848. London, Balliere, Publisher, 219 Regent street.