A superb German microscopical compendium, signed G.F. Brander Aug. Vind. fecit. [Augsberg] circa 1770

Details

A superb German microscopical compendium, signed G.F. Brander Aug. Vind. fecit. [Augsberg] circa 1770

This compendium consists of three main components plus accessories:

1. a screw-barrel microscope constructed in gilded brass, with a
brass and ivory handle;

2. a scioptic ball set in an ebony and gilded brass circle in a
square walnut frame;

3. a compass microscope in gilded brass with the lower part of the
handle in ivory

4. accessories: eleven objectives, five of which are in silver
lieberkuhns; a set of four screws and nuts to attach the frame
to a window shutter; gilded brass tweezers; forceps; a card case covered in tan-coloured Buntpapier holding six wooden
sliders; an ivory and card cylinder to attach the crew-barrel to the scioptic ball; and a micromter ruling on glass.

The screw-barrel microscope 2.6/10in. (6.7cm.) long, 1.1/8in. (2.9cm.) diameter is to the popular pattern introduced to London by James Wilson in 1702, which was produced by Edmund Culpeper and his contemporaries and successors. In order to convert the simple microscope, which the screw-barrel is, to a compound microscope, there is an ivory tube 3.3/4in. (9.5cm.) long that attaches to the screw-barrel by a gilded brass ring, an attachment also made by Culpeper. This tube has a single eye lens of about 1-inch (2.5cm.) focal length. Six objectives (lowest power about 12 mm focal length) in brass mounts are provided. These can be used with both the simple and compound microscope arrangements, the latter taking the lower power objectives especially. They function as the projection lens when the screw-barrel is attached to the scioptic ball. They can also be used with the compass microscope.

The ebony scioptic ball 2.1/10in. (5.3cm.) diameter has freedom of movement, within an ebony retaining ring, over a wide range so that it may be set to receive through the central hole direct light from the sun to project the image of a specimen onto a screen. When set, the position of the ball is clamped by four screws with wing heads, fitted through the brass ring that bears the maker's signature. The frame 7in. (17.7cm.) square holding the ball has to be attached over an aperture cut into a window shutter, and four iron screws and four anodized brass nuts are provided for this purpose. At each side of the ball is a brass ring, on the sun side to retain a lens, and on the room side to provide a screw attachment for the ivory cylinder with a short draw-tube. To this is fitted the screw-barrel, with a suitable objective to project the image of a specimen in a slider, which is held in place by the slot in the screw-barrel. The ivory cylinder allows optimum adjustment of the illuminating system.

The compass microscope 8in. (20.2cm.) long is also to the pattern produced by London makers, especially John Cuff. It is made so that one leaf is hinged and is held by a threaded rod against a U-spring, the separation for focusing addjusted by a knurled wheel. The lens holder is threaded to accept any of the six objectives, or any one of five objectives mounted in silver lieberkuhns, which reflect light from around the specimen being examined back onto it. On one side is fitted a holder for the forceps on a long rod, the opposite end of which ends in a point, which may be used on its own, or over which may be pushed a black/white disc, or a two-pronged fork.

A pull-top case holds six sliders each with eight apertures. The sliders are probably of limewood. One is empty so that the owner of the compendium can mount specimens to choice. For this purpose, the two ivory boxes hold mica slips (often known as talcs) and split rings. The other seven sliders contain specimens such as fleas, legs and wings of insects, feathers, and shavings of wood.

The glass micrometer is a particularly interesting feature in this magnificent set of microscopes. The ruling is on a disc of glass (19mm.) diameter held in an anodized brass cell. This in turn is contained in an ivory box, with a circle of blue velvet at the bottom to protect the ruling. The micrometer is in the form of a square net, the lines composing it being ruled with a diamond point. From the eighteenth century and through the nineteenth, optical instrument makers used the Paris line as the international standard of length. A line is one twelfth of a Paris inch, which is 27 mm long, so the line measures 2.25 mm. Brander's micrometer has a central part 2 lines in width, divided into 20 parts, thus each division is one tenth of a line. At each side of the central part are two rulings half a line apart. The execution is highly skilled, and this micrometer is in mint condition.

All the items pack into a walnut case, with the base in soft wood, the inside with shaped wooden supports all covered with cream coloured chamois leather. The lower part is edged in silver braid. The case measures 15.3/4 x 10 x 3.5/8 inches (40.2 x 25.7 x 9.3cm.)

See Colour Illustration and details

Literature

Alto Brachner, editor, G.F. Brander 1713-1783: Wissenschaftliche Instrumente aus seiner Werkstatt (Munich, Deutsches Museum, 1983).

G.L'E. Turner, The Great Age of the Microscope: The Collection of the Royal Microscopical Society through 150 Years (Bristol and New York, 1989), 249-257, 339-347.

Ernst Zinner, Deutsche und niederlandische astronomische Instrumente des 11. - 18. Jahrhunderts (Munich, 1956), 256-263.

Lot Essay

The Maker
Georg Friedrich Brander was born at Regensburg in 1713, and studied mathematics at the university of Altdorf. He founded his workshop at Augsburg, and from 1737 until his death in 1783 he manufactured every type of philosophical, mathematical, and optical instrument. He began to make glass micrometers from 1761, for which he became famous. These were used in microscopy, and also in astronomy. It is thought that Brander's interest in making microscopes was due to the publication at Augsburg in 1754 of the German translation of Henry Baker, Employment for the Microscope (London, 1753). be this as it may, there is no doubt that the designs of the London makers influenced Brander when he made this microscopical compendium.

In 1755, Brander had the idea to improve measurement in microscopy by producing rulings on glass that could be placed directly in the image plane. Consequently, he began to design a ruling machine, which was successful in producing glass micrometers by 1761. The achievement was later published by J.H. Lambert (1728-1777), "Beschreibung der von G.F. Brander neuerfundenen Glasmicrometer" (1768). From 1760, Brander employed Christoph Hoschel, and when in 1775 he married Brander's daughter, he was taken into partnership, and instruments were henceforth signed: "Brander & Hoschel in Augsburg". These dates imply that the compendium was made between 1761 and 1775.

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