DESCRIPTION:

An early microscope attributed to Hugh Powell Ca 1840.

This microscope, from the collection of Dr Jurriaan de Groot*, is signed “Dollond London”, and arises from a heavy circular brass base 5 ¼ inches (135 mm) in diameter. A sturdy circular pillar carries the pivot point for the Lister-limb which has been machined in one piece. The tail end carries a one-sided concave mirror 45 mm(1.8 inches) in diameter.

The coarse focus is operated by two knurled heads working through a pinion carried within a slider attached to the body tube, the mechanism being internally sprung by a roller bearing from the other side to eliminate any forward and backward slack and also sprung from the right side internally to prevent right-left slack. The rack is embedded into the upper part of the front of the limb.

The main part of the tube is short and measures only 115 mm in length, with a 35 mm(1.4 inch) long extension of smaller diameter upon which the nosepiece fine adjustment works. As such the mechanical optical tube length is only 6 inches (152 mm) in total. The eyepiece has a push fit diameter of 32.3 mm(1.3 inches), sits flush with the body tube and magnifies approximately x 10.

The circular mechanical stage is 3 ½ inches(89 mm) in diameter. Movement is accomplished by two knurled knobs positioned in the 135 degree & 225 degree positions, at right angles from one another to move the central rectangular stage plate. There is a single U-shaped stage clip to hold the slide. The rectangular stage support has a hole into which the stage forceps fits.

The objective thread is identical in pitch and diameter (17 mm) to the pre- RMS Powell & Lealand thread. The objectives are similar in appearance and finish to those made by Hugh Powell, and also featured on another microscope signed by Cornelius Varley elsewhere on this site.

Accessories include a generously proportioned stage forceps, polarized light apparatus, plus three bone sliders numbered 1,2, and 3.

When purchased, two early Powell objectives 1/8 in. and 1/16 in. were present. Since then a pre-RMS Powell ½ in (with Lieberkuhn) , and 2 inch objective were added to the set. The 1/16 inch (dry) objective has an exceptionally short working distance, and a N.A. of approximately 0.64 characteristic of the earliest version of this objective as first developed by Hugh Powell in 1840.

The mahogany case measures 335 x 185 x 130 mm(13.2 x 7.3 x 5.1 inches), and its cushioned lid is reminiscent of cases also used for Carpenter and Westley microscopes.

This microscope stands some 380 mm(15 inches) tall when focused, and is of compact dimensions , but nevertheless weighs 4.825 Kg (10 ½ pounds), due to its solid construction.

Although not signed by Powell, this instrument shares many features with his other signed examples, as can be seen in the illustrations, and is of the same high standard of workmanship and finish. Compare the pillar, inclination joint, and fine focus controls. The accessories including the objectives, eyepieces, and unusually-mounting stage forceps are essentially identical to known Powell examples. It was probably made for the trade around 1840, and retailed by Dollond, not long before Hugh Powell went into partnership with his brother in law Peter Lealand.

HISTORY OF HUGH POWELL MICROSCOPES

Hugh Powell is first mentioned in the literature in 1831, regarding the first of three simple dissection microscopes made by him for Cornelius Varley (1781-1873). They both lived in the same neighborhood of London, Somers town. It is also known that Powell was making mechanical microscope stages designed by the engraver, Edmund Turrell, who also produced some of Varley’s illustrations for The Transactions of The Society of Arts, so there were many interconnections between men involved in microscopy.

Varley’s nephew was Andrew Pritchard (1804-1882), and for some time Hugh Powell made a number of microscopes for him, whilst other examples of this Pritchard design were signed and retailed by other opticians, such as Bate, and Dollond.

In 1840, the newly formed Microscopical Society commissioned Messrs Hugh Powell, Andrew Ross, and James Smith each to furnish a standard instrument made to their own peculiar views.

Powell’s massive model(left) as delivered to the Society is still part of the R.M.S. collection today, and features a solid triangular post, as well as the first example of an English microscope equipped of an achromatic condenser. A small number of this large model continued to be made until 1849. Note the bulge on the limb housing the pressure bearing, a feature which is also integretated into the microscope shown on this page.

For more information about the history of P & L, please see the History Section of the pages devoted to the P & L number one.

*We are very grateful to Dr Jurriaan de Groot for sharing his images and information about this microscope with us so you can enjoy it on this site.