486 SCIENTIFIC RECORD FOR 1882 



fit to have experiments tried iu its light than before." {Nature, October, 

 XXVI, p. 572.) 



Liveing and Dewar have studied carefully the lines in the spectra 

 of different elements which have been supposed to be coincident, and 

 conclude, from the results that they have already obtained, that the coin- 

 cidences as yet unresolved will yield to still higher dispersive power or 

 are i>urely accidental. {Ann. Chim. Phys., February, Y, xxv, p. 190.) 



Langley has given the results of experiments made with the bolome- 

 ter to determine the distribution of energy in the normal spectrum. 

 This curve has its maximum ordinate very near the line D, the meas- 

 urements extending from a wave length of 0.00035 to 0.00300"^™. Taking 

 the bolometric indications when the sun was nearest the zenith, and 

 when at a distance from it, the author has been able to calculate the form 

 of the curve of solar radiation without the earth's atmosphere. This 

 curve has its maximum ordinate near the line F, whence he concludes 

 "that the total radiations of the solar photosphere, if they could reach 

 us, would give us the sensation of a compound color resembling a dark 

 blue." {Ann. Chim. Phys., February, Y, xxv, p. 211.) 



At the Southampton meeting of the British Association, Langley 

 gave the results of his bolometric measurements made upon the sum- 

 mit of Mount Whitney, in Southern California, at an altitude of 13,000 

 feet. These, combined with the results obtained at Allegheny, gave 

 tlie data for two charts, one of the prismatic, the other of the normal, 

 spectrum. The extension of the spectrum by these measurements is 

 remarkable. Between H in the extreme violet and A in the furthest 

 red lies the visible spectrum, its length being about 4,000 of Ang- 

 strom's units. The chart shows that the region below this extends 

 through 24,000 units more, so much of it as lies below wave-length 

 12,000 being here mapped for the first time. Moreover, the bolometer 

 shows this region to be crossed by Fraunhofer lines ; and, with the aid 

 of one of Eowland's concave gratings, their wave-lengths have been 

 measured. The terminal ray of the solar spectrum whose presence has 

 certainly been felt by the bolometer has a wavelength of about 28,000. 

 He concludes with the remark that " while all radiations emanate from 

 the solar surface, including red and infrared, in greater degree than 

 we receive them, that the blue end is so enormously greater in propor- 

 tion, that the proper color of the sun as seen at the photosphere is blue — 

 not only bluish, but positively and distinctly blue." {Nature, October, 

 XXVI, p. 586.) 



Several new forms of direct-vision prisms have been suggested. 

 Ahrens uses a bisulphide prism cemented between two flint-glass prisms 

 giving a wide dispersion with but little loss of light. Fuchs employs 

 a single isosceles glass prism at minimum deviation, a silvered mirror 

 being attached to the basal face of the prism tr» rectify the ray after 

 emergence. Ricco has described a similar combination, in wbicb a total- 

 reflection prism is substituted for the mirror. The second x)rism of the 



