September 12, 1907] 



NATURE 



5»« 



tules, and art schools. In thirty-six London County Council 

 schools, centres for instruction in commercial and science 

 and art subjects will be opened. These centres are in a 

 degree contributory to the polytechnics and technical insti- 

 tutes mentioned above and are nriniarily intended for 

 students not sufticiently aavanced 1-jr the ^lylechnic classes. 

 Advanced work, however, is tai<eii !n imny of thi: subjects. 

 In 237 London Counly Council school buildings situated 

 in every part of London, ordinary evening schools will be 

 opened this session. The instruction will, as a rule, be of 

 a character preparatory to that given in the centres. 



Till', educational demands of the organised workers of 

 this country are expressed in the following points of a 

 resolution adopted at the Trade Union Congress at Bath 

 last week : — (i) The State maintenance of school children. 

 (2) .Scientific physical education with individual medical 

 inspection, and records of the physical development of all 

 .children attending Siale schoolk, and skilled medical 

 attendance for any requiring it, and in order to secure 

 this : — (a) The formation of a properly staffed medical 

 department at the Hoard of Education, the head of which 

 shall be directly responsible to the Minister of Education, 

 to whom he shall report annually. (6) 'I he payment of 

 an adequate grant from the Imperial Exchequer for pur- 

 poses of medical inspection, (c) The establishment under 

 every education authority of scientifically organised open- 

 air recovery schools, the cost to be borne by the com- 

 munity as a whole, and not in any part by charitable con- 

 tributions. (3) The complete dissociation of reforms (i) 

 and ii) from Poor Law administration. (4) A national 

 system of education under full popular control, free and 

 secular from the primary school to the univcrsily, 

 (S) That secondary and technical education \it an essential 

 part of every child's education, and secured by such a 

 reform and extension of the scholarship system as will 

 place a maintenance scholarship within the reach of every 

 child, and thus make it possible for all children to be full- 

 time day pupils up to the age of sixteen. (6) That the 

 best intellectual and technical training be provided for the 

 teachers of the children, that each ed'.';<'ional district 

 shall be required to train the number of pupil t/:aehers 

 'demanded by local needs, and to establish training colleges, 

 preferably in connection with universities or university 

 colleges. . (i) That the provision of educational buildings 

 and facilities be obligatory upon the local authority, who 

 shall always retain administrative control of the buildinjjs 

 and facilities so provided. W) That the cost of e<lucation 

 shall be met by grants from the Imperial Exchequer, and 

 by the restoration of misappropriated educational endow- 

 ments. (9) That it be an instruction to the Parliamentary 

 Committee of the Trade Cnion Congress to formulate 

 these proposals in a Bill to be laid before Parliament 

 during the forthcoming session. 



Fkom tables published in Science of August 30, it 

 appears that the total number of degrees of doctor of 

 philosophy and doctor of science conferred by the universi- 

 ties of the United States this year was 327, which is 

 almost exactly the 'same as in 1905 and 1906, v/hen the 

 numbers were, respectively, 325 and 32O. The average 

 number for the past ten years is 271, Of 2715 doctorate 

 degrees conferred during the past ten years, 1232, t^jme- 

 what less than half, have b«en in the natural and exact 

 sciences. The relative proportion of degrees in the 

 humanities and in the vJences has not alt/rred appreciably 

 in the ten years covered by the statistics. The Johns 

 liopkins Jias ^Mnferrerl more degrees in the sciences than 

 any other institution, but is closely followed by Chiirago, 

 and at a not very considerable distance by Harvard, 

 Columbia, and Yale, f-ifty-five per cent, of the degrees 

 conferred at the Johns Hopkins have been in the s/;iences, 

 and 57 per cent, at Cornell, whereas in th*- other leading 

 institutions the percentage is decidcdely less — ^> at 

 Chicago, 42 at Harvard and Columbia, and 40 at Vale 

 and Pefimsylvania. Of the /232 degrees conferred in the 

 sciences during the past t<rn years, chemistry leads with 

 320 d'>< torafes ; then follow in order of numbers, physics, 

 J55 ; z'/ology, 147; psychology. 134; botany, 126; and 

 mathematics, 121, The remaiiyler of the deffrees are 

 divided among fourt/ren other' sciences, meteorology and 

 geography being at the bottom of the list with one 

 doctor.-ite each. 



NO. 1976, VOL. 76] 



SOCIETIES AND ACADEMIES. 

 London. 



Royal Society, June 27. — "(-M the I'orce rei)uir«d lo Slop 

 a .Moving Kleclrified Sphere." By <j. !•". C. tearia, 

 I-.k.S. 



If 1'' be the force which must be applied in the sphere 

 at any time /, after it has been brought lo rest at <'U, 

 the positive direction ol I'' being oppusile lo that of u, 

 the initial velo<:ity, the niomeiiliim given up by the electro- 

 magnelir field froiii ( <i lo ( ( is 



/>"■ 



()uring this period the force !• does no work, since the 

 sphere is at rest, and hence the energy is unchanged 

 during this period. 



At the time t let the sphere be restarted with the same 

 velocity « without change of direciioii, and lei !"• Im; ihc 

 force which must be applied to thr- sphere at any sub- 

 sequent time in the direction of u in order to maintain 

 the velocity «. This fone lasts from ( -( to (■ (', where 

 t' — t is determined by the condition that in the time 

 t'-t the pulse formed on restarting the system has com- 

 pletely passed over Ihe sphere. During the interval t' — t, 

 the momentum is increased by 



/■'' 



and henic ilie lolal gain of momentum is 



During ilie 

 creased by 



('(■„//- ('V'il. 

 lervai (' -(, the e 



^y In 



"!>'■ 



The stopping and the restarting of the sphi^re each give 

 rise to a pulse, and the compound pulse so formed carries 

 ofT energy W and momentum I". Before the system was 

 stopped the energy of the electromagnetic field was U+T 

 and its momentum was M, and at an infinite time after 

 the stopping and restarting the energy is U-f-Tn-VV' and 

 the momentum is SI + 1", sinc« the energy and momentum 

 in the parts of the field outside the i:<jm|K(und pulse 

 ultimately vanish. 



Equaling the two expressions for the gain of momentum, 

 we have 



Similarly, 



("c,<Jt ['VrJl=\". 



FJ/^W'/u-l", 



(0 



and thus we find that the force n-quifA to slop the 

 system is given by 



This force will heconv: wtro as soon as W'/«-l" t"^- 

 comes constant, which will occur as soon as t is so great 

 •hat the two pulses due to the stopping and restarting 

 do not overlap. 



It follows from (z) that, if I', be the torij; required to 

 stop a sphere of radius a with a uniform surface- 

 charge Q, 



where v is the velix;ity of light. W'tutn thr: sphere ha« 

 a uniform volume-charge 



Pakih. 



Academy of Science*, Keptemlxrr 2, — M. A. Chaoveau fn 

 tlie chair. — ('aryolysis in the nid/jrian glands </f (innetta 

 tenegalenui : Joannes Cbatln, A study of nuclear 

 degeneration in the jjerineal glands. It is shown itiat 

 this is a cav; of true <aryoly»is, exa/.tly <xirre»(A/nding to 

 the disapfxrarance of the nucleus in the truir %trh:v'M» 

 cell. — I>hv«icallv similar fluids : M. JouKuat. I lie ax t ion 



