Descriptive catalogue of optical instruments and apparatus constructed and sold by Watkins and Hill, 5 Charing Cross, London.

  • Watkins and Hill.
Date:
[between 1860 and 1869?]
Catalogue details

Licence: Public Domain Mark

Credit: Descriptive catalogue of optical instruments and apparatus constructed and sold by Watkins and Hill, 5 Charing Cross, London. Source: Wellcome Collection.

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    264. Model to illustrate the principle of Wheatstone’s Polar Clock, ^1 Is. 265. Wheatstone’s Polar Clock for shovdng the hour of the day by the polarizing power of the atmosphere. This apparatus is of a large size, and is intended for use as a fixed instru¬ ment, ^2 12s. 6d. 266. Portable form of Wheatstone’s Polar Clock. This instrument is made on a small scale for the convenience of carrying in the pocket; it has all the necessary adjustments, and is provided with spirit levels, and a magnetic compass, and packs in a neat case, £2 12s. 6d. 267. Biot’s Apparatus for examining the circular Polarization of Fluids, consisting of a glass tube for holding the liquid, with silver stops, mounted in a brass case on a ball and socket stand, with a plane black mirror, polarizing plate, and a double refracting achromatic analysing prism, £4 4s. 268. Powell’s Apparatus for examining the circular Polarization of Fluids, consisting of a series of glass tubes of various lengths, capable of being mounted in brass adjusting tubes, with polarizing mirror and analysing prism, mounted on brass stand complete, 8s. DIFFRACTION, &c. 269. Reade’s Iriscope, consisting of a polished black glass plane mirror with its surface covered by a thin dried film of fine soap, which when breathed upon through a glass tube, ex¬ hibits a series of brilliant coloured rings by the vapour deposited, 10s. 270. Barton’s Iris Buttons, to illustrate the prismatic or iridescent appearance of white light reflected from grooved surfaces. The phsenomena are shown by the sun’s or oxyhydro¬ gen lime fight, and the iridescent image may be thrown on to a screen or the ceiling of a darkened chamber, with the most beautiful effects, 7s. 271. Fraunhofer’s Gratings or Screens, from the Optical Institute of Munich, of very fine paral¬ lel equidistant right-lined and curved fines, ruled in gold leaf on plates of glass, £2 2s. and £2 12s. 6d. 272. Prisms with equal angles mounted on silvered plane reflecting mirrors, for illustrating the interference of fight; vdth or without microscopic arrangement. 273. Prisms for interference of fight, with very obtuse angles, 6s. each. 274. Potter’s Heliostat. This instrument, so useful in many optical experiments where the sun’s fight is required to be reflected on a given spot for a length of time, is of a simple and convenient form, motion being given to the mirror by a watch movement. It is provided with levels, leveling screws, silvered and black glass mirrors, and an extra double mirror, by which the pencil of fight may be thrown in any desired direction.