yo 



NA TURE 



[NOVKMHKK 17, 1898 



bequest of the late A. W. (;. Allen. The studentship is of the 

 value of 250/., is tenable for one year, and is oix'n in alternate 

 years to students proposing approved courses of research in ( I ) 

 literary subjects, or (2) scientific subjects. 



Seventy-live candidates have presented themselves during 

 the past year for the Sanitary Science Kxamination. Of these 

 thirty-nine were successful in obtaining the University diploma 

 in I'ublic Health. 



The Knginecring Laboratory Syndicate have lost no lime in 

 proposing a plan for the Hopkinson Memorial Building. The 

 new wing will adjoin the j)resent laboratory, and provide a 

 lecture-room, three laboratory-rooms, and small rooms for 

 students engaged in research. For the completion of the plan 

 some 500/. will be required, in addition to the 5000/. generously 

 given by Mrs. Hopkinson and her children. It is e.\pecled 

 tliat the building will be ready for occupation in October 1S99. 



Mr. W. N. Shaw, F. R.S., was on November 10 appointed 

 Assistant-Director of the Cavendish Laboratory for one year. 



In Berlin the (lowers gathered in the town gardens are 

 placed in the municipal schools for the purpose of furthering 

 the study of botany. Arrangements have now been made by 

 the London School Board, and will come into operation in 

 April next, whereby a gardener will collect, pack, and forward 

 to the schools of the Board botanical specimens and flowers, 

 budding plants, leaves, A:c., required for leaching botany or 

 for objccllessons, or for the combination of drawing and object- 

 lessons. 



It is expected (stales the /^//k/m^'k///) that the London Uni- 

 versity Commission will commence its sittings this month. Mr. 

 Bailey Saunders, the secretary, has been collecting information 

 in (jermany, especially concerning the organisalion of higher 

 commercial education, which svill be made an important 

 element in the newly constituted university, with the co-opera- 

 lion, it is hoped, of the London County Council. It is probable 

 ihal ihe headtjuarters will be removed from Burlington Gardens. 

 Christ's Hospital is talked of as the new site. 



Tllli Calendar of the Imperial Tientsin University for the year 

 1897 has been received. The University was established towards 

 the end of 1S95, ""'' ''s faculty includes several graduates of 

 colleges in the United States. Mr. C. I). Tenney is the 

 president. Prof. Oliver C. Cliflord occupies the chair of 

 chemistry and jihysics, I'rof. K. t;. Adams Ihe chair of civil 

 engineering, and I'rof. N. F. Drake the chair of mining. Most 

 of the tutors and teachers are natives of China. It is announced 

 that last year his F.'icellency Li Chung-la'ng shoived his good 

 will towards the University by a present of a 4-inch telescope, a 

 phonograph, and several things for the physical laboratory. 



Al.l>ERM.\N John Hopkinso.n, the members of his family, 

 and near relatives, have oflered to the Owens College, Man- 

 chester, in memory of the late Dr. John Hopkinson, a gift of 

 1600/., to cover the expense of building the dynamo house 

 connected with the new physical laboratory. It is ho|)ed 

 that by additional contributions from friends who desire to see 

 a suitable memorial of Dr. Hopkinson in Owens College, 

 where he was a student for three years, it may be possible 

 to complete and equip the annexe containing in addition to 

 the dynamo house a number of other rooms devoted to 

 eleclrolechnics, and that the whole may be known as the 

 "Dr. John Hopkinson Electrotechnical Laboratory." 



SOCIETIES AND ACADEMIES. 



London. 

 Physical Society, November II.— Mr. Shelford Bidwcll, 

 F.K.S., President, in the chair.— The di.scussion on Mr. .Albert 

 Campbell's paper on the magnetic lluxes in meters and other 

 electrical instruments w.is resumed. I'rof. Ayrton saiil he 

 wished to offer .some remarks on behalf of Mr. Mather and him- 

 self. The paper would, jierhaps, have received more ade<|uate 

 discussion at the Institution of Ivlectrical ICngineers, for it was 

 chiclly of a technical character. The importance of neutralising 

 Ihe effect of leads when using inslrumenls with very weak 

 fields, such as a Siemens' electro-dynaniomeler, should be 

 emphasised. In instruments of the Kelvin-balance type where 

 two opjioscd coils carry two opposed currents, Ihe lield spreads 

 at the edges ; the true " working " (hix is not that directly 

 between the coils. Mr. Cam|)bell would have done better if 



NO. I 5 16, VOL. 59] 



he h.ad used a long search coil wound round one of the swinging 

 coils, forming part of a vertical cylinder. It would have lieen 

 well also to have supplied some experimental proof that the 

 asLitic arrangement of^ the swinging coils of the Kelvin balance 

 makes the instrument independent of the earth's field. The 

 effect of the earth's field is of the order o'2, so that with 

 instruments of the Weston type, with a field of the order 1000, 

 it was sometimes assumed, erroneou.sly, that the readings were 

 practically independent "of the earth's H. I'rof. .Ayrton's own 

 tests showed that by turning a Weston voltmeter towards 

 different points of the compass, the errors in a particular case 

 were far greater than might be predicted from the above ratio ; 

 the induction in the voltmeter pole-space, due to the earth's 

 field, was much higher than 0'2 ; the earth's field was ex- 

 aggerated by the iron pole-pieces ; it was not necessary to sup- 

 pose that the magnetism of the permanent magnet caused the 

 variation. The error observed was about 02 per cent, in a 

 horizontal field, and u'S percent, when the field of the volt- 

 meter was parallel to the earth's induction. Here the induction 

 in the gap was 1200, and H = 02. In tests relating to the 

 Ayrton and I'erry magnifying-spring voltmeter, it was more 

 important to know the B in the air-space near the iron than the 

 B tvilltin the iron. Kddy currents might account for the 

 extraordinary results obtained with the Shallenberger meter. 

 Mr. J. II. Reeves described a method he had adopted for 

 measuring the effect of stray fields upon ammeters and volt, 

 meters. The instrument to be tested is first mounted on a 

 sland and is brought under the influence of a large coil 

 carrying a current. In this way, fields of known magnitude 

 can be superimposed on the working field, throughout the range 

 of the instrument, and the change of dellection due to them 

 can be observed. I'rom these known values, the working 

 field can be deduced. For let the current in the solenoid of 

 the instrument at any moment be A amperes, producing a 

 corresponding unknown working field of magnetic force X. 

 Then .\ is proportional to the solenoid current, as measured by 

 the indications of the instrument. If a m.agnetic force .1 is 

 superimposed on .\, then .r is measured by .v/."< of A. If .> is 

 known, the working field X can be calculated from the change 

 of dellection produced by the superposition. With Evershed 

 ammeters, the field measured in this way was in one instrument 

 200, and in another 226 ; or about one-third of Mr. Campbell's 

 figure (700) for ihe Evershed ammeter. -Mr. Campbell's value 

 of B did not represent the working field, but the field at the end 

 of one of the fixed pieces of iron. Mr. Campbell, in reply, said 

 he thought the theory of electrical instruments to be well within 

 the limits of physics, and he had for that reason presented the 

 paper to the Physical Society. The position chosen for the 

 search coil in the Kelvin-balance tests may not have corre- 

 .sponded to the working flux, but it was near to the right 

 position, and he had carefully specified the position chosen. His 

 results as regards the Weston instrument differed from those of 

 Prof. Ayrton, the errors he had observed for the |)articular 

 ammeter used were under O'l per cent. The earth's field 

 probably produced .an effect different for ilifferent We-ston 

 instruments, .according to the degree of saturation of the 

 i)ermanent magnet. In Mr. Campbell's tests, the Weston 

 instrument did not have an iron case. — A paper by Prof. W. B. 

 Morton, on the propagation of damped electrical oscillations 

 along parallel wires, was then read by Prof. J. D. Everett. In 

 a paper published in the /'///'/. Mag. for September 1898. Dr. 

 E. H. Barton compared the attenuation of electrical waves in 

 their passage along parallel wires, as experimentally determined 

 by him, with the formula given by Mr. Heavisidein his theory of 

 long waves. He finds close agreement as regards the effect of 

 a terminal resistance, but large discrepancy in the case of the 

 attenuation constant. Prof. Morton now investigates how far 

 the results should be modified when it is supposed, as under actual 

 conditions, that the oscillations propagated fiom the origin 

 are damped, and that the circuit is not balanced, as in the ideal 

 case of distortionless transmission. He finds (\) that the 

 velocity of propagation is increased, while (2) the attenuation 

 is increased, and (J) with infinite resistance between the ends 

 of the wires, the waves are, as before, reflecteil completely with 

 phase unchanged. .\s the resistance is diminisheil ihe ampli- 

 tude of the reflected waves is decreased, and a phase-difference 

 is introiluced. I'or a certain value of the resistance the re- 

 flected amplitude is a minimum, and ihc pliase-diliercnce is »/2. 

 When the resistance is zero there is again complete reflection, 

 with the phase-diflereiice ir ; /.■■. Ihc waves are reversed. The 



