616 



PHYSICS, PROGRESS OF, IN 1893. 



arrears. Before defaulting, the Government 

 attempted to prove a breach of contract on the 

 part of the corporation, and the courts imposed a 

 fine of 5,000, which was not collected because 

 the charges were frivolous. The Congress re- 

 fused to authorize the Government to cancel the 

 contract. It agreed to a proposition to increase 

 excise duties 50 per cent., and passed a bill re- 

 establishing the gold currency and prohibiting 

 the importation of silver coins. Ihe editors 

 who had been prosecuted were allowed by act of 

 Congress to print their newspapers again. Gen. 

 Caceres was declared to be a traitor, and a bill 

 was passed to deprive him of citizenship on the 

 ground that he had granted to Ecuador a part 

 of the Peruvian territory when he was President. 

 A new boundary treaty with Ecuador was re- 

 jected. At the close of October the most seri- 

 ous rioting of the year took place. The fol- 

 lowers of Caceres demanded the dissolution of 

 Congress and an immediate election of a new 

 President. The police countenanced the dis- 

 turbances, but not the ministers, who threatened 

 to resign if energy could not be shown in re- 

 pressing disorder, and who prevailed upon the 

 President to order out the military. 



PHYSICS, PROGRESS OF, IN 183. 

 Constitution of Matter. Ether and Matter. 

 Prof. O. Lodge (British Association) has con- 

 tinued his experiments to detect a possible drag 

 exerted by matter on ether. He has been able 

 to rotate two disks of tough steel a yard in diam- 

 eter and an inch apart 8,000 times per minute 

 without obtaining evidence of such drag. An 

 oblate spheroid of wrought iron weighing a ton 

 and magnetized by a current sent through a 

 wire wound around it in a deep groove was also 

 rotated without effect. 



The Fourth State. Lord Kelvin (London 

 Royal Society, Nov. 24) has followed out the 

 hypothesis that the phenomena of the Crookes 

 cathode stream are caused by inelastic molecules 

 whose energy, by impact on the tube, is spent 

 entirely in heating the glass. Taking the mass 

 of matter in 1 cubic centimetre as equal to 10- 8 , 

 and the velocity to be 100,000 centimetres per 

 second, the final temperature is 875 about that 

 found experimentally. The pressure would be 

 about 100 milligrammes per square centimetre 

 ample for the observed mechanical results. The 

 assumed velocity is too small to affect the optical 

 color test, and Kelvin concludes that there is no 

 objection to the Crookes doctrine of a cathode 

 stream. 



Mechanics. Foundations of Dynamics. An 

 extended discussion on the fundamental axioms 

 of dynamics has been carried on by Prof. 0. 

 Lodge, Prof. McGregor, of Nova Scotia, and 

 others, chiefly in the " Philosophical Magazine " 

 and " Nature," one of the subjects of discussion 

 being an attempt by Lodge to restate the laws 

 of motion in terms of energy. In one of his new 

 laws he asserts the continued identity of every 

 portion of energy. This he upholds (" Nature," 

 Jan. 16) on the ground that energy, like matter, 

 is always passed on continuously through space. 

 Heaviside, in reply, instances gravity as an ex- 

 ception, but Lodge asserts that even if gravity 

 be passed on instantaneously, as if by a thrust of 

 an incompressible body, it is none the less passed 

 continuously. 



Potential. F. W. Dyson (at the meeting of 

 the London Royal Society, April 20), in discuss- 

 ing the potential of an anchor ring, finds that a 

 rotating ring is stable for fluted and twisted 

 disturbances, but unstable for long, beaded ones. 

 This has an important bearing on certain astro- 

 nomical theories. 



Elasticity. G. F. Becker ("American Journal 

 of Science," November) finds that if Hooke's law 

 were exactly true, sensible changes of pitch 

 would occur during the subsidence of vibration 

 in strongly excited bodies. He deduces the fol- 

 lowing formula, which is not open to this ob- 

 jection : In (a?h) = ~, where a = ratio of shear 



due to the traction Q, h=* ratio of linear dilata- 

 tion, M= Young's modulus, and n= modulus 

 of distortion. 



Grinding and Polishing of Solids. Lord Ray- 

 leigh (British Association), in experiments on the 

 grinding and polishing of glass by emery, finds 

 that the former process is not a scratching, as 

 has been generally supposed, but a formation of 

 isolated pits or depressions, and that the polish- 

 ing then removes molecular layers till the level 

 of the bottoms of these pits has been reached. 

 The polishing was good when a thickness equal 

 to 2 wave lengths of sodium light had been re- 

 moved, and was perfect when 4 wave lengths 

 had been taken. 



Gravity. Mascart (Paris Academy of Science, 

 Jan. 80) details the results of observations made 

 at Pare St. Maur Observatory for many years, 

 which show variations in the intensity of gravity. 

 The instrument used was a barometer tube in 

 which the mercury was balanced by hydrogen 

 confined in an adjoining vessel. Daily variations 

 were observed, as well as sudden variations 

 which he thinks must have been due to displace- 

 ments in the mass of the earth. Some of these 

 lasted fifteen to sixty minutes, and caused a dif- 

 ference in the level of the mercury of -05 milli- 

 metre. D'Abbadie (ibid.. Feb. 6) asserts that ob- 

 servations on falling bodies begun in 1837 in 

 Brazil have made the constancy of gravity doubt- 

 ful. He proposes to call Mascart's instrument a 

 brithometer (Greek brithos, weight). Bouquet 

 de la Gorge (ibid., Feb. 20), of the Depot de la 

 Marine, has made observations with a similar in- 

 strument that indicates the change of the moon's 

 position by an alteration of level of 46 milli- 

 metres. A. Berget (ibid.), using a similar instru- 

 ment, which he calls a hydrogen gravimeter, has 

 observed the effect of a change of level of 1 

 metre in a lake 79 acres in extent, reading the 

 slight alteration of level in his instrument by a 

 method depending on the use of interference 

 fringes. He deduces as the value of the gravita- 

 tion constant 6'80 x lO" 8 , and as the density of 

 the earth 5'41. Richarz and Krigar-Menzel have 

 finished a series of observations on the density of 

 the earth that have been carried on by them in 

 the citadel of Spandau since 1887. By balancing 

 two heavy masses at different vertical distances 

 below the balance beam, and then changing their 

 places, it is found that the difference between the 

 values of y for a change in level of 2'26 metres is 

 6-523 x 10- 6 . The value calculated from other 

 data is 6-970 x 10' 6 . The discrepancy is due per- 

 haps to the presence of strata less dense than the 

 average. 



