January 6, 1910J 



NA TURE 



>87 



suit. It would be scarcely too much to say that for 

 the last thirty years this subject occupied the attention 

 of the deceased astronomer. The care and elaboration 

 M. de la Grye bestowed on the reduction of the 

 observations, sometimes devising' ingenious experi- 

 ments to remove photographic diflRculties, at others 

 undertaking new determinations of longitude in order 

 to improve the data, are beyond all praise. 



M. de la Grye's attention to geodesy supplied 

 him with another outlet to his energy, and 

 perhaps a relaxation. As a member of the 

 Bureau des Longitudes, he interested himself 

 in all questions which involved the figure of 

 the earth, tidal movements, the variation of gravity 

 or of latitude. He was a regular attendant at all 

 geodetic congresses, reporting their proceedings and 

 upholding their objects. The proposed scheme for 

 the re-measurement of an arc of meridian in Peru had 

 his hearty support. In the details he took the greatest 

 interest, and his suggestions were appreciated by the 

 commission. The encouraging support he was ever 

 ready to extend to others, and his long experience, 

 always at flie command of those who sought his 

 counsel, will be long missed by his colleagues, who 

 well know how irreparable is their loss. 



PROF. J. S. H. PELL AT. 



IT is with deep regret that we see the announcement 

 of the death, after a very short illness, of M. 

 Pellat, professor of physics at the Sorbonne (Paris). 

 Joseph Solange Henry Pellat was born at Grenoble 

 on July 27, 1850, and he died on the December i8 

 last. After leaving the Ecole normale superieure, he 

 started work as meteorologist in the Paris Observa- 

 tory. His stay there was not long, however, for he 

 was soon appointed as professor in the College Rollin, 

 and then at the Lycee Louis-le-Grand. In 1885 he 

 was appointed a lecturer in the faculty of science at 

 the Sorbonne, and was ultimately given a chair, 

 which was created specially for him. He occupied 

 many distinguished positions. He was for many 

 vears general secretary of the French Physical Society, 

 and also occupied the presidential chair. He was 

 vice-president in 1896 of the Society des Electriciens, 

 and was president of the same society at the time 

 of his death. 



Prof. Pellat was one of a brilliant group of pupils 

 of Prof. Jamin, whose laboratory at the Seine was a 

 focus for physical studies. His scientific work covers 

 nearly the whole range of physics. Of practical 

 importance we may single out his construction of an 

 electrodynamometer, in which the force is measured 

 by which one coil is pulled inside another when a 

 current flows through each. Measurements of the 

 jlectrochemical equivalent of silver and experiments 

 on the cadmium cell fall within the same category. 

 It was, however, for questions having a theoretical 

 bearing that he had the greatest interest. Some of 

 his early work consisted in measuring the differences 

 of potential of contact between two metals ; and 

 throughout his life, in common with practically all 

 French physicists, he adhered to the views then held 

 as to the existence and origin of these potential- 

 differences. In a paper in the Journal de Physique 

 for March, 190S, lie combated the theorv of Nernst in 

 regard to the performance of a voltaic cell, and con- 

 sidered that his experiments proved that a metal 

 immersed in a solution of one of its salts is sensibly 

 at the same potential as the latter, at any rate when 

 the solution is not too dilute. 



Prof. Pellat was greatly interested in the proper- 

 ties of dielectrics ; he constructed apparatus for 

 measuring dielectric constants, and also (in 1899) for 

 NO. 20Q7, VOL. 82] 



measuring their rate of change with temperature. 

 The latter data were required to illustrate the applica- 

 tion of a theorem deduced by him thermodynamically-, 

 according to which the increase of the energy of "a 

 condenser on being charged is only partly represented 

 in general by the electrical energy, an intake (posi- 

 tive or negative) of heat occurring at the same time 

 whenever the dielectric constant varies with tempera- 

 ture. In 1895 he promulgated a new method of deal- 

 ing with electrostatic phenomena in the general case 

 of heterogeneous dielectrics, in which Coulomb's law 

 is dispensed with, and use is made of three experi- 

 mental principles in conjunction with the two laws of 

 thermodynamics. In an early paper on the influence 

 of a metal on the nature of the surface of another 

 metal placed a small distance away from it, he antici- 

 pated one of the modern phenomena of rays bv show- 

 ing that lead emits something capable of affecting 

 a neighbouring photographic plate in the dark. 



Of his devotion, zeal, and enthusiasm, M. Bouty 

 speaks in the funeral oration (Revue scientifique for 

 January i), from which we have gleaned many of 

 the above facts. He lived as in a beautiful dream. 

 The taste for experimenting he had contracted as a 

 youth. His experimental ingenuity was never at 

 fault. He had furnished his laboratory with appar- 

 atus of his own invention. His lectures swarmed with 

 original experiments. "Pellat had inherited a name 

 rightly celebrated in juridical science. He transmits 

 it to his widow and children shining with an added 

 light." 



DUKE KARL THEODORE OF BAVARIA. 

 'T'HE subjoined extract from the official gazette of 

 J- the Principality of Monaco, referring to the 

 death of Duke Karl Theodore of Bavaria, is worthy 

 of being put on record as an appreciation of one great 

 personage of high rank by another, and an acknow- 

 ledgment that the nobility of station which commands 

 the greatest respect is that which carries with it 

 personal service to the community. 



Son Altosse Royale Charles-Thtedore, Due en Bavifere, 

 qui vient de mourir dans Sa residence de Bad Kreuth, 

 6tait le beau-pire de Son Altesse le Due d'Urach et Sa 

 disparition atteint profoad^ment le Prince Albert dans Ses 

 affections les plus chores. 



L'alliance entre la Famille des Duos en Bavi^re et 

 celle des Princes de Monaco n'avait pas, seule, rapproche 

 les deux Princes ; il e.xistait aussi entre Eux une sympathie 

 <5troite bas^e sur la communaut^ de Leurs goOts pour le 

 travail scientifique et le progr^s des idiSes. 



Le Due Charles-Theodore, aprfes avoir fait de brillantes 

 Etudes m^dicales, S'^tait specialise dans I'oeulistique et 

 pratlqua avec une habilete qui Lui attira une clientele 

 considerable: non pas celle qui apporte k I'operateur une 

 fortune, mais eelle qui, au contraire, sort de chez lui 

 moins pauvre qu'elle n'y etait entree. 



Charles-Theodore fonda des cliniques, et ce Prince qui, 

 d6s sa jeunesse, avait sent! qu'une couronne royale impose 

 avant tout la pratique du bien, y fit des operations tris 

 nombreuses. Dans cette tache que Sa haute intelligence 

 se donnait, il etait seconde par Sa femme dont le coeur 

 formait le digne pendant du Sien. Et le couple exemplaire 

 vivait ainsi depuis trente-quatre ans sans §tre separe un 

 seul jour, si ce n'est quand I'Empereur Guillaume. blesse 

 i I'ceil, demanda les soins du Due. Sa residence de 

 Kreuth, situee au milieu des Alpes Bavaroises, loin des 

 elegances mondaines, devenait vers le mois d'octobre le 

 lieu de reunion d'une nombreuse famille que plusieurs 

 amis, des confreres ou des professeurs, rejoignaient tou- 

 jours avec joie. Alors se succedaient les chasses au cerf 

 ou au chamois, celles qui se font dans les conditions 

 vigoureuses, seduisantes pour des chasseurs de race : et 

 le Prince Albert y trouvait regulierement, depuis seize 

 ans, la compensation de Sa vie laborieuse. 



II faut pleurer avec tout son coeur la disparition du 



