896 Intelligence and Miscellaneous Articles. 



ings were small triangular ebonite plates which were fastened to 

 the side of the glass vessel. The cylinder turned slowly and con- 

 tinuously with currents of 0*1 to 1 ampere. The motion gradually 

 became slower, in the first place probably because the surface of 

 the cylinder became rough, owing to electrolysis. After going for 

 some time the motion appeared to become more uniform. Some 

 experiments gave an approximate proportionality between the 

 velocity of rotation and the strength of the current. It is possible 

 that in the hands of a skilled technicist this might lead to the con- 

 struction of a continuous electricity meter for continuous currents. 

 — Wiedemann's Annalen, No. 2, 1892. 



ON A METHOD OF DETERMINING ELECTROMAGNETIC RADIATION. 

 BY PROF. KLEMENCIC. 



The method applied by the author consists in bringing a thermo- 

 element near a fine platinum wire heated by the electric vibrations, 

 and measuring the increase of temperature of the junction. As a 

 comparison the platinum wire is also heated by a constant current, 

 and the rise of temperature of the junction is also measured. Two 

 series of experiments were made. In one the author employed a 

 form of secondary inductor which has frequently been used (two 

 thin brass plates each 30 cm. in length by 5 cm. in breadth), and 

 investigated the heating of a thin platinum wire 2 cm. in length. 

 The observations showed a production of heat of 0*000155 calorie 

 per second. In the second case, a single platinum wire 26*3 cm. in 

 length was exposed to radiation, and the value 0*000088 calorie 

 per second obtained. In both series of experiments Hertz's 

 mirror was used with a distance of 1*44 metres between the focal 

 lines. It may in addition be mentioned that a wave-length of 66 

 cm. corresponds to the primary inductors, that the Kuhmkorff was 

 excited by three accumulators, and that the breaks were at the rate 

 of 23 per second. Boys, Briscoe, and Watson (Phil. Mag. 1891, 

 xxxi. p. 44) determined the intensity of the electromagnetic radia- 

 tion with the aid of the convection air-thermometer, and found the 

 value 0-000685 calorie per second. The length of the wire they 

 used was 2 x 103 cm., and it was at a distance of 30 cm. from a 

 couple of primary inductors of above 100 cm. in length. If the 

 value found by the English physicists is referred to unit length of 

 the irradiated wire, and if this is done also for the second value 

 found by the author, the result is a production of heat in both 

 cases of 0*000033 calorie per second. Owing to the great differ- 

 ence between the two methods, this agreement is of course only 

 accidental. — Wiener Berichte, February 18, 1892. 



