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Inventory no. 47114 - Former Display Label

English COMPOUND MICROSCOPE
c.1761

A Cuff type 'Double' microscope signed on the stage "Dollond LONDON". Inset in the top of the box foot is a brass plate inscribed "D. D. JOHANNES TUNNADINE LL.D.". Brass stand fixed to square mahogany box with drawer, and contained in a pyramidal mahogany case with drawer in base. The non-inclinable stand has a pillar in two parts, one sliding over the other when focusing. The approximate positions in which the limb has to be placed for each of the six object glasses is indicated on the pillar by appropriately numbered marks. To adjust the fine focus the limb is clamped to the pillar and a knurled wheel at the top of a vertical screwed rod is turned; this type of fine focus was employed by John Marshall c. 1695.

The body tube incorporates double convex eye-lens, field-lens, and objective-lens; there is no draw-tube. The stage is fitted with top-illumination condenser lens, stage forceps with black/white disc and Bonnani stage. Integral with the brass base is a concave mirror. Among the accessories is a lieberkuhn mirror, in a brass box, and its carrier, which is a brass tube, part cut away, that slides over the nose piece. Other accessories include: six objective lenses in brass mounts, a brass cone that fits under the stage and intended to cut off oblique rays when using the highest powers, a live box, being two brass mounted discs of glass which, screwed together, leave a narrow space to contain insects, two concave glass discs to hold drops of liquid, a deeper glass for holding a greater quantity of liquid, a fish plate with securing ribbon, a black fish-skin box containing 8 ivory slides with a list of the microscopic objects contained therein, an ivory box containing spare talcs [i.e. discs of mica] and brass retaining rings, a brush set in a quill for cleaning glasses, a brass demountable slider with spare slips of glass, a length of brass wire with a helix at one end for manipulating small fish in glass tubes. Among the accessories most probably with the instrument when it was originally sold but now lost are, glass tubes to hold small fish, a hand magnifying lens, and tweezers.

Included in the cabinet is a pamphlet A Description of the Compleat Microscopic Apparatus: as made and sold by John Dollond and Son, Opticians ..., London 1761.

[BHK]
Lent by Christ Church, Oxford

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