Chemistry and Physios. 411 



The practical unit of light is called the decimal light and is the 

 one-twentieth of the absolute standard defined by the Interna- 

 tional Conference of 1884. 



The bougie decimale is sensibly equal to the English candle — 

 or to one-tenth of the Carcel burner. — Comptes Rendus, Sept. 2, 

 1889, p. 393. J. T. 



5. Lightning and the Eiffel Tower. — The Eiffel tower was 

 struck by lightning on the 19th of August, 1889, and Professor 

 Mascart gives a short account of the occurrence in a note to the 

 French Academy. The tower is protected by a central rod at its 

 summit and by rods projecting from the balustrade of the third 

 platform. The lightning discharge passed down the central 

 lightning rod. Various subsidiary discharges were noticed at 

 different parts of the tower by the four attendants who were on 

 the tower at the time. The cloud which touched the top of the 

 tower was vividly lighted. None of the four persons on the 

 tower received the slightest shock although the iron work of the 

 tower was wet by the shower. Professor Mascart remarks that 

 security to life is absolute on a tower of this construction. — 

 Comptes Rendus, Aug. 26, 1889, p. 355. j. t. 



6. Transmission of power by Electricity .—M.. Deprez states 

 that power has been transmitted regularly for some months from 

 a fall of water to the village of Bourganeuf, a distance of 14 

 kilometers. The line which transmits the current is of bronze 

 silicieux (pure copper). The wire is 5mm. in diameter, uninsu- 

 lated and is supported on wooden poles furnished with porcelain 

 insulators. The generator and motor are ring-formed and furnish 

 100 nominal horse power. The electromotive force of the genera- 

 tor is 3000 volts. — Comptes Rendus, Sept. 2, 1889. J. t. 



7. Dissipation of negative electric charges by sunlight and day- 

 light. — J. Elster and H. Geitel show that the dissipation of 

 negative charges can be caused not only by the ultra violet rays, 

 but also by sunlight and diffuse daylight. — Ann. der Physik tend 

 Chemie, No. 9, 1889, p. 40. ■ j. t. 



8. Photography of the invisible portions of the Solar Spectrum-. 

 — M. Ch. V. Zenger states that one prism of rock salt combined 

 with two rectangular prisms of an'ethole gives between the lines 

 A and D six times the dispersion of one prism of rock salt. The 

 arrangement is called by Zenger a parallelopiped of dispersion. — 

 Comptes Rendus, Sept. 9, 1889, p. 434. j. t. 



9. The Carbon Spectrum. — H. Kayser and C. Runge have 

 examined the band spectra of carbon given by the electric light 

 between carbon terminals in order to see if these band spectra 

 coincide with those of cyanogen. The results of their measure- 

 ments force them to conclude that the identity of the cyanogen 

 spectrum and the carbon spectrum has not been made out. They 

 give an empirical formula for the arrangement of lines in the 

 band spectra of carbon, and state their belief that the true law of 

 the arrangement of lines in the band spectra can only be arrived 

 at from a theoretical discussion of the law of molecular move- 



