238 Intelligence and Miscellaneous Articles. 



For want o£ space I cannot give here the details of the observa- 

 tions, but only the result of the calculations — that is to say, the 

 values of I, I', I" for the three needles, combining the series of ob- 

 servations successively in threes : — - 



Series 



f A 



A,B,D. A,C,E. B,C,F. D, E, F. 



milliin. millim. millim. millim. 



Bar 1 78-1 78-3 78-1 



„ II 70-0 69-8 .... 69-8 



„ III 61-6 .... 61-7 61-9 



„ IV 49-6 49-9 49-6 



I may remark that, once the polar distances are determined, the 



same experiments will furnish the value of the ratio — — , necessary 



in order to measure the intensity of terrestrial magnetism by G-auss's 

 method. — Convptes Rsndus de VAcademie des /Sciences, Jan. 8, 1877, 

 tome lxxxix, pp. 76-78. 



PHOTOGRAPHS OF THE SPECTRA OF VENUS AND a LYR.E. 

 NOTE BY PROF. HENRY DRAPER, M.D. 



Since the spring of 1872 I have been making photographs of the 

 spectra of the stars, planets, and Moon, and particularly, among 

 the stars, of a Lyrae and a Aquilae, with my 28-inch reflector and 

 12-inch refractor. In the photograph of a. Lyrae, bands or broad 

 lines are visible in the violet and ultra-violet region unlike any thing 

 in the solar spectrum. The research is difficult and consumes 

 time, because long exposures are necessary to impress the sensitive 

 plate, and the atmosphere is rarely in the best condition. The 

 image of a star or planet must be kept motionless for from ten to 

 twenty minutes ; and hence the driving-clock of the telescope is 

 severely taxed. 



During last summer I obtained good results, and in October 

 took photographs of the spectrum of Venus which show a large 

 number of lines. I am now studying these pictures, and have sub- 

 mitted them to the inspection of several of my scientific friends, 

 among others Professors Barker, Langley, Morton, and Silliman. 

 There seems to be in the case of Venus a weakening of the spec- 

 trum toward H and above that line, of the same character as that 

 I have photographically observed to take place in the spectrum of 

 the Sun near sunset. — Silliman's American Journal, February 1877. 



ON THE SPECTRA OF METALS AT THE BASE OF FLAMES. 

 BY M. GOUY. 

 It is known that a flame produced by a mixture of coal-gas and 

 air, in proportions suitable for burning without the help of the ex- 

 ternal air, has for its base an inner cone, at the surface of which 

 the combustion commences. This surface is brilliant, of a blue or 

 green colour, and gives the spectrum of carbon. The experiments 

 which I am about to relate show that this same surface gives a very 

 different spectrum from that of the flame of which it forms the base 

 when the combustible mixture holds in suspension saline powders. 



