404 



SCIENCE. 



[N. S. Vol. VIII. No. 195. 



water in anything but a mathematically 

 smooth pipe cannot be rigorously treated by any 

 of the methods of rational mechanics, for the 

 very troublesome characteristic of all un- 

 stable states of a system is that subsequent 

 aspects of the system are influenced to a finite 

 extent by infinitesimal initial causes. The flow 

 of water in a pipe is, in its details, about as 

 difificult to rationalize as the weather. 



THE SYNCHRONOGRAPH. 



Professor A. C. Crehore and Lieutenant 

 G. O. Squier have devised means for using 

 individual pulsations of a sinusoidal alter- 

 nating current for signalling in high-speed 

 telegraphy. Their Synchronograph, as the 

 instrument is called, has been tried by the 

 inventors on some of the lines of the British 

 Post OfBce, and the results show that the 

 Synchronograph is capable of transmitting 

 words from three to seven times as fast as 

 the Wheatstone apparatus at present in use. 



SCIENCE ABSTRACTS. 



A NEW periodical of the above title is now 

 being published under the direction of the 

 Physical Society of London and of the 

 British Institution of Electrical Engineers. 

 This journal aims to give a complete ab- 

 stract of current literature in physics and 

 electrical engineering. It certainly has 

 good reason to be, and it will no doubt prove 

 to be of great usefulness to English-speak- 

 ing physicists and engineers. The ab- 

 stracting of (foreign) physical papers in the 

 Proceedings of the Physical Society is dis- 

 continued. 



CATHODE RAYS. 



Sir Wm. Crookes' original hypothesis 

 that cathode rays consist of rapidly-moving, 

 negatively-charged particles is proving to 

 be increasingly useful in leading to and in- 

 terpreting new experiments. Lenard * has 

 recently measured the variations of velocity 

 of cathode rays, which are produced when 

 the rays pass parallel to the lines of force 



»Wied. Ann., Vol. 65, p. 504. 



in an electrostatic field — afield independent 

 from that which produces the raj's. These 

 measurements were made by observing the 

 deflection of the rays by a magnetic field. 

 The velocity of the cathode rays, calcu- 

 lated from the observed deflection, ranges 

 from j\ to \ of the velocity of light. These 

 variations of velocity were also clearly in- 

 dicated by observed variations of the de- 

 flection produced when the altered cathode 

 rays were passed at right angles to an aux- 

 iliary electrical field, though the author 

 did not calculate the various velocities in 

 this case from the observed electrostatic de- 

 flections. 



Merritt* has shown that cathode rays 

 reflected from a platinum obstacle have the 

 same velocitj^ as the incident rays — that is, 

 to say the reflected and incident rays are 

 equally deflected by a magnetic field. If 

 the moving particles in the cathode rays 

 are about -j-^Vtt ^^ massive as hydrogen 

 molecules, as has been pointed out by J. J. 

 Thomson, then these particles should show 

 but little diminution of velocity after im- 

 pact with platinum molecules, and corre- 

 sponding to this the reflected and incident 

 rays should be equally deflected by a mag- 

 netic field. 



THE ELECTROCHEMICAL EQUIVALENT OF 

 SILVER vs. THE MECHANICAL EQUIVA- 

 LENT OF HEAT. 



Rowland's value of the mechanical 

 equivalent of heat, reduced by W. S. Dayf 

 to the Paris hydrogen temperature scale, is 

 distinctly different from the value of this 

 equivalent as determined electrically by 

 Grifliths and by Schuster and Gannon. 

 The electrical metliod involves the electro- 

 chemical equivalent of silver, inasmuch as 

 the measurement of current was carried out 

 in these experiments by means of the sil- 

 ver voltameter. A redetermination of the 



* Paper read before Section B at Boston. 

 ■\Fhysical Review, VII., 193. 



