

V. REFLECTION, ETC. 197 



914. Jamin's Optical Bank of Diffraction. 



H. Lloyd, Trinity College, Dublin. 



914a. Jamin's Apparatus with Parallel Mirrors. 



M. Lutz, Paris. 



914b. Large Steel Mirror. M. Lutz, Paris. 



914c. A Series of Barton's Iris Buttons, consisting of 

 gold and steel faces engraved upon which are numbers of very fine 

 lines, illustrating most beautifully iridescence or decomposition of 

 light from grooved surfaces. The lines on the large steel button 

 are 100, 200, 400, 500, 1,000, 2,000, and 4,000 to the inch. 



Robert C. Murray, London. 



915. Optical Bank, improved by Professor Clifton, of 

 Oxford, to observe the interference and diffraction of light and 

 measure the bands. Elliott Brothers. 



915a. Photographed Diffraction Gratings, the originals 

 by Nobert, 6,000 and 3,000 lines in a square inch. 



Lord Rayleigh. 



For description see accompanying pamphlet, from Philosophical Magazine. 



91 5b. Collection of Six Gratings (rcscaux) by Nobert in 

 Barth, and Steig in Homburg. Foundation Teyler at Haarlem. 



Nobert B. of 1,801 grooves on six Paris lines. 



C. of 3,001 



., D. of 10,801 on one Paris inch. 



E. of 2,001 



F. of 3,001 

 Steig A. of 3,201 grooves on five millimetres. 



Nobert B and C were used by Prof. Van der Ur'lligen fo the determination 

 of the wave-lengths of fifty lines in the solar spectrum. 



91 5c. Specimens of circular Gratings (Reseaux) photo- 

 graphed on Glass. The rays of the successive circles limiting 

 the opaque and transparent parts are in the proportion of 1 to 

 A/2, \/3, \/4, 57&c. 



91 5d. Large Grating (Reseau) on smoked Glass, trans- 

 parent traces of equal width, having rays" in the proportion of 

 >/3, \/T, VTH VT5, VT9, &c. J. Louis Soret, Geneva. 



See " Memoire sur les Phenomenes de Diffraction produits par les Keseaux 

 circulates " (Archives des Sciences physiques et naturelles, 1875, Vol. 52, 

 p. 320. PoggendorfPs Anualeu, 1875, No. 9). 



915e. Telescope for Circular Gratings (Reseaux). Con- 

 structed by the Geneva Association for Constructing Scientific In- 

 struments. /. Louis Soi-et, Geneva. 



