Conversazione : Burlington House May 9th, 1934.

  • Royal Society
Date:
1934]
Catalogue details

Licence: Public Domain Mark

Credit: Conversazione : Burlington House May 9th, 1934. Source: Wellcome Collection.

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    35. The Department of Comparative Anatomy and Zoology, Cambridge, and The Cambridge Instrument Co. Ltd. The Development of the Automatic Microtome. The first suggestion of an automatic microtome originated with W. H. Caldwell, of Cambridge, in 1882. He discovered that if objects were embedded in hard paraffin wax, and the block was given a surface coating of soft paratfin, consecutive sections adhered on their edges to one another, so that they could be cut in a long continuous ribbon. R. H. Threlfall, then an under- graduate at Cambridge, co-operated with Caldwell in the construc- tion of what was the first automatic microtome, Threlfall being responsible for the mechanical design. The original instrument made in the Engineering Laboratory at Cambridge is exhibited, and sections of 2:5uy in thickness may still be cut with it. In 1885 Horace Darwin, in consultation with Caldwell and Threlfall, devised the well-known “Cambridge Rocking Microtome.” During the fifty years since it was introduced the instrument has undergone various modifications, although it has not been altered in any fundamental point. Instruments showing the progressive modifications, and some of the recent developments, are exhibited. 36. Department of Mineralogy, British Museum (Natural Hostory). Silica-glass from the Libyan Desert (Dr. L. J. Spencer, PLS). This material was recently discovered by Mr. P. A. Clayton during the work of the Egyptian Desert Surveys in the unexplored region bordering on Italian Cyrenaica, about 500 miles S.W. of Cairo. Wind-worn lumps up to 10 lb. in weight were found acattered on the surface between the sand-dunes over an area of 80 by 25 kilometres. Some artificially worked flakes were also found. The material is a nearly pure silica-glass containing SiO, 97:58 per cent. It is pale greenish-yellow in colour and usually quite transparent, and when cut and polished it makes quite an effective gemstone. One of the cut stones exhibited is lent by Mrs. 8. L. Courtauld. No evidence was obtained on the spot to explain the origin of this silica-glass. It is quite distinct from the fulgurites formed by lightning. It resembles most closely the still problematical tektites ; while the presence of a trace of nickel suggests a relation to the silica-glass found around meteorite craters,
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