Abstract
ADAMS appears to have given a great deal of consideration to the method of measuring magnification of microscopes, and illustrates in detail in the “Micrographia Illustrata” (Plate 14), fourth edition, various micrometers for this purpose, amongst others the micrometer he made in 1761 for the silver microscope of George III. This instrument originally formed part of the King's collection and is now in the Lewis Evans collection. It has been described by Messrs. Clay and Court at some length.1 Although the details of workmanship in this instrument are excellent, the instrument as a whole must be regarded as an ornament rather than a serious contribution to microscopy. Such is not the case with the earlier instrument made for the King when Prince of Wales, and known as the “Prince of Wales” microscope (see Fig. 2). It is particularly interesting as embodying the method of mounting a microscope on trunnions; perhaps, as Clay and Court remark, the first microscope so supported. There are three stages, one of which (shown in the bottom of the illustration) is of great interest, having micrometers registering in two directions at right angles. The screws have 100 threads to the inch, and the scales on the heads are divided into 100 parts, so that the micrometers read to 1/10,000 inch. The stage shown in position on the microscope was intended to carry a frog for demonstrations of the circulation of the blood. It is a matter of general knowledge that King George III. was keenly interested in scientific matters, and wished that his family should be instructed in science. Dr. Demainbray commenced to teach the Royal family in 1754, and appears to have used for this purpose the apparatus which formed the major part of what is known as the King George III. collection. The instruments in the collection were catalogued in a manuscript book which is still preserved in the Kew Observatory, and also in a catalogue which is now in the Science Museum at South Kensington. The instruments were housed at the Kew Observatory until 1841, when they were transferred to King's College, London. In 1925 they were removed to the Science Museum at South Kensington, where the majority of them can be studied. The story of the collection was told in some detail in a paper before the Optical Convention of 1926.2 The majority of the instruments intended for instructional purposes were made by George Adams, although few of them bear his name. Fortunately two books of instructions have been preserved, and it is by means of these that it is possible to state that the majority of the instruments were made by Adams.†
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References
"Two Microscopes made by G. Adams for King George III." By R. S. Clay and T. H. Court . Jour. R. Micr. Soc., pp. 268–273; 1926; and Supplementary Note, Jour. R. Micr. Soc., p. 255; 1927.
"An Old Catalogue and what it tells us of the scientific instruments and curios collected by Queen Charlotte and King George III." By R. S. Whipple . Proc. of the Optical Convention, Part II., 1926.
"Mathematical Elements of Natural Philosophy, confirmed by Experiments: or an Introduction to Sir Isaac Newton's Philosophy." Written in Latin by the late W. James's Gravesande, LL.D., Professor of Mathematicks at Leyden and F.R.S. Translated into English by the late J. T. Desaguliers, LL.D., F.R.S., and Published by his son J. T. Desaguliers. Sixth Edition 1747.
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WHIPPLE, R. Some Scientific Instrument Makers of the 18th Century*. Nature 126, 283–286 (1930). https://doi.org/10.1038/126283a0
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DOI: https://doi.org/10.1038/126283a0