Chemistry and Physics. 77 



The difference from the mean is half a wave, or about one-fourth 

 of a micron. We can thus compare two standards by means of 

 light waves with the same order of accuracy that we can at pres- 

 ent compare the meter bars, and the comparison is based upon an 

 unchangeable unit. — Nature, Nov. 16, 1893. j. t. 



11. Radiation of heated gases. — F. Paschen, by means of a bolo- 

 meter, has conducted a series of experiments upon the radiation 

 of heated air, oxygen, carbonic acid and steam. The gases were 

 heated by passing over a platinum spiral which was raised to in- 

 candescence by a storage battery. A heat spectrum was formed 

 and wave-lengths as long as 5 - 2<m were measured. It was found 

 that gases can emit a discontinuous spectrum. In the case of 

 C0 2 and steam, there was a displacement of the intensity within 

 the emission maxima, with decreasing temperatures. No expla- 

 nation is given of this phenomenon. — Ann. der Physik and 

 Chemie, No. 11, 1893, pp. 409-443. j. t. 



12. Electric radiations in Copper Filings. — At a meeting of the 

 Physical Society, London, Oct. 27, Mr. W. B. Craft stated that if 

 a battery-galvanometer and tube containing copper filings were 

 joined in series under ordinary conditions no current passed ; but 

 a current was immediately produced by an electric spark, pro- 

 duced many feet distant by an electrical machine. Iron filings 

 were inferior to copper, and carbon always allowed the current 

 from the battery to pass. — Nature, Nov. 9, 1893, p. 46. j. t. 



13. Absorption of Electrical waves. — I. Klemencic has applied 

 his method of the thermal junction to the question of the absorp- 

 tion of the energy of electrical oscillation on wires of different 

 material and confirms the results of Bjerknes, J. J. Thomson and 

 Trowbridge in regard to the damping effect of iron. For wires 

 made of iron, german silver, brass and copper of 6 cm long and 

 q. 0i gem c "li ame ter he finds the development of heat can be ex- 

 pressed relatively as 10-5 : 1*75 : 1 : 1. The observations showed 

 that in the case of the ramification of electrical waves of very 

 short duration the factor of self-induction is more potent than 

 that of resistance. — Ann. der Physik and Chemie, No. 11, 1893, 

 pp. 456-475. j. T. 



14. A new form of Contact maker. — In a paper read before a 

 late meeting of the American Institute of Electrical Engineers, 

 Messrs. Bedell, Miller and Wagner describe a new form of con- 

 tact maker. A fine jet of water was projected upon a needle 

 which is inserted into a revolving disc, and thus contact was made 

 between a voltmeter and a circuit. The nozzle of the water jet 

 is carried by a disc which is capable of being rotated and has its 

 edge graduated into degrees. The voltmeter could thus be con- 

 nected with the circuit of a transformer at any required part of a 

 cycle. The needle cut the water jet before it broke into drops. 

 A little salt was put into the water, for conduction. j. t. 



