Notes

Abstract

ONE of the most effective methods of acquiring a headache is a good round of sightseeing, especially in a museum, collection, or picture-gallery; it is quite a comfort to get among a collection of any kind, the sight or catalogue of which does not make one ill by anticipation. Happily the headachy feature is generally absent from the collection of objects exhibited at the Royal Society conversazioni, and in this respect and because of its great interest, the collection brought together last Wednesday week was quite a model. Prof. Snellen's two modes of testing for colour-blindness ought to have been the first thing looked at, because then the guests would have been in a position to estimate the value of their observations. The inspection caused much amusement, and in some cases astonishment. The “Mechanical Chameleon”, to exhibit the mixture of two colours in any proportion, was interesting, as was also Woodward's new rectangular prism illuminator, to be used with immersion lenses. The Presidents photographs of scenes and objects in the Rocky Mountains were specially attractive. Other objects which attracted considerable attention were—A large Holtz electric machine (by Ladd) consisting of twelve rotary and twelve stationary plates, thirty inches diameter, exhibited by Mr. W. Spottiswoode, Treas. R.S. A microspectroscope with improvements,—(1) quick movement of the slide carrying the slit; (2) scale for registering position of slit; (3) arrangement for comparing three spectra, and for splitting a single spectra; (4) new form of comparison stage, made by Mr. A. Hilger. A dynamo-electric machine, speed 800 revolutions, power 1.75 H.P. required to work it, effect 1,200 candles' light, exhibited by Messrs. Siemens Bros. The telephone harp, with visible records of sound through vacuum tubes, exhibited by Mr. F. A. Gower. Apparatus for showing figures in light from vibrations caused by sound, exhibited by Mr. Henry Edmunds. A metallic thermometer, invented by Mr. H. Bessemer; and apparatus for the automatic registration of the number of hours of sunlight, made for Kew Observatory, exhibited by Mr. J. Browning. A phoneidoscope, an instrument for observing the coloured figures reflected from liquid filters under the action of sonorous vibrations, made and exhibited by Tisley and Co. Composite portraits, made by combining the likenesses of different persons into a single resultant figure: (1) optically, (2) photographically, exhibited by Mr. Francis Galton, F.R.S.; we hope to publish a paper on the subject next week. We need not say that the phonograph in operation, under the superintendence of Mr. Preece, was specially attractive, and that Winkler's Lunar Landscape, and the beautiful photographs and paintings exhibited, lent a delightful variety to the collection.