Chemistry and Physics. 399 



8. Photography applied to the flight of birds. — M. Marey con- 

 tinues his researches upon this subject and shows that his method 

 of taking photographs of the flight of a bird on a horizontal and 

 also on a vertical plane enables one to reproduce the phenomenon 

 of flight in a zoetrope, and also to study the mechanism of flight. 

 He shows that previous observers have greatly exaggerated the 

 rise and fall of a bird's body during flight. — Comptes Pendus, 

 Sept. 5, 1887, p. 422. • j. t. 



9. Spectra of Hydrogen, Oxygen and Water Vapor. — Pro- 

 fessor GRtiiSrwALD of Prague enunciates the following theory of 

 the relationship of the spectra of gases and their compounds. 

 Let \ci\ be the volume occupied by a primary chemical element, 

 a in the unit of volume of a gaseous substance, A. Let A be 

 chemically combined with a second gaseous body, B, to form a 

 third, C. The element a now takes the form a 1 and the volume 

 \ci\ Then the wave lengths, A, of the lines in the spectrum of 

 A, which belong to. a, are to the wave lengths, A', of the lines in 

 the spectrum of C, which belong to a', as [a] is to [a 1 ]. The 

 wave lengths of the elementary spectrum of hydrogen can be 

 arranged into two groups, a and b, which give the lines of the 

 water vapor spectrum when they are respectively multiplied by 

 i-g- and |-. The author concludes that hydrogen is composed of 

 the combination of four volumes of the element a with one of the 

 element b. The first element, a, should be the lightest of gases 

 and lighter than hydrogen. Since it must therefore enter into 

 the constitution of the corona, Professor Griinwald calls it cor- 

 onium. The D 3 or helium line is found in the spectrum of the 

 element b, and the author therefore calls b the helium line. The 

 correspondence between the wave lengths calculated by this 

 theory and those actually observed is striking. — Phil. Mag., Oct., 

 1887, p. 354. j. t. 



10. Earth currents. — M. Landerer gives, as the result of his 

 observations during the past nine years, that, on the special line 

 employed by him, the general direction of currents is from 

 south to north. If the frequency of the currents from northeast 

 to southeast be denoted by 1, that of currents in the opposite 

 direction will be 6*7. The maximum intensity occurred about 

 10 a. m. — Comptes Rendus, Sept. 12, 1887, p. 463. j. t. 



11. Electrical standards. — A committee of the British Associa- 

 tion upon this subject submitted, at the late meeting at Manches- 

 ter, the following resolutions : " 1. To adopt for a term of ten 

 years the legal ohm of the Paris Congress as a legalized standard 

 sufficiently near to the absolute ohm for commercial purposes. 

 2. That at the end of the ten years period the legal ohm should 

 be defined to a closer approximation to the absolute ohm. 3. 

 That the resolutions of the Paris Congress with respect to the 

 Ampere, the Volt, the Coulomb, and the Farad be adopted. 4. 

 That the resistance standards belonging to the committee of the 

 British Association or electrical standard now deposited at the 

 Cavendish Labora'ory at Cambridge be accepted as the English 

 legal standards, conformable to the adopted definition of the 



