272 MICROTOME 1789 (88fJ Fig. 240
By George Adams, London
Baseboard 221 x roo, plate 210 x 7®, height to plate 118; bpfdr'length 108, maximum
width 2i, possible length of specimen about 30.
Four brass pillars on a mahogany baseboard support a flat brass plate pierced with
two parallel grooves. A pin in each groove holds the cutting knife by a spring so that
the cutting edge presses downwards. The knife is pushed along the grooves across
the hole through which protrudes the specimen, the angle of the blade with respect
to the direction of movement being 150. After a cut the specimen is advanced by a
screw with a micrometer wheel divided in five units. The specimen holder is in the form
of a cylindrical segment, radius 17 and chord 19. The microtome was despatched by
Adams in September 1789, and cost -£ 6 (see Cat. 269).
The study of the structure of timber was one of the few scientific studies with
the microscope during the 18th century. This microtome is designed specifically ro cm
thin sections of wood, It seems to be an improvement on the instrument illustrated by
Adams in his Essays in that the blade is positioned rather better in relation to the
specimen. A hole has been made in the baseboard for easier insertion of a long piece
of wood.
Adams (1787) 124, IX, fig. T; Thomas (1968}. • ••
Inv. 6g!6
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273 CABINET OF MICROSCOPE SLIDES « 1790 (365/1) Fig. 241, 242
By Abraham Ypelaar, Amsterdam
Si gned in the booklet listing the specimens: A. Ypelaar & Comp, te Amsteldam
Cabinet 200 x 105 x 624 sliders 80-83 x I2j cells of diameter 12.
A mahogany cabinet holds four drawers, three of transparent objects in ivory sliders,
and one of opaque objects in circular cells made of ivory. The booklet is pre-printed
with numbers, and the name of the objects entered by hand. It is inscribed: “ Trans-
parante en Opacque Voor Werpen voor het Microskoop Geprepareert door A. Ypelaar
& Comp, te Amsteldam” . The thirty-six sliders each hold four specimens that