Nov. i8, 1875] 



NATURE 



59 



*nd the results which have been obtained in the main verify those 



of Mr. Iluggins as to the approach and recession of stars from and 



towards us in the line of sight. The Astronomer Royal remarked 



that Mr. Huggins had in this direction had the privilege of 



\rting a new science, and it would be their duty at the Obser- 



ory to revise it ; they intended to follow up the matter still 



■her, but there were great diftlculties still to be overcome, 



■culties which no one could appreciate who had not attempted 



icate work of the kind. They had also at the Observatory 



jii applying themselves to photography, and had taken nega- 



esof the sun with considerable regularity, though there were 



. er spots to be observed now than at any former period which 



could remember. Sir G. B. Airy also laid before the Society 



ap of the stars in the neighbourhood of Mars during its next 



osition in 1877, and drew attention to the great advantages 



ich this opposition would offer for the determination of the 



ir parallax. — Mr. De la Rue gave an account of the prepara- 



ns that are being made both in France and Austria for the 



cultivation of physical astronomy. At Vienna an observatory is 



n the course of erection outside the city, on an area of some 



een or seventeen acres. A central dome is being erected of 



. feet in diameter, which is to hold a 2 7- inch refractor, by 



.bb, of Dublin. — Prof. Pritchard gave an account of the new 



vsical Observatory at Oxford, and of the mounting of the 



; inch refractor by Grubb, which has recently been bought by 



University. — Lord Lindsay read a note on the progress of 



■ reduction of his observations of the transit of Venus ; and 



■. Bidder exhibited at the meeting and described an observing 



-ir of simple and inexpensive construction. 



Physical Society, Nov. 13. — Proi. Gladstone, F.R.S., 

 oiident, in the chair. — The President stated that since the 

 t meeting of the Society, Prof. Everett's important work on 

 J Centimetre-Gramme-Second System of Units had been 

 lished by the Society. The book is based on the recora- 

 udations of a committee of the British Association, and con- 

 3 or a collection of physical data concisely presented on the 

 jve system, a complete account being added of the theory of 

 its. — Dr. Stone then read a paper on Thermopiles. He has 

 .ently been engaged in some experiments with a view to ascer- 

 1 the best alloy for use in thermopiles. The thermo-electric 

 v.er of a metal or alloy appears to be quite unconnected with 

 power for conducting heat or electricity, or with its voltaic 

 Nation to other metals, neither does it appear to have any rela- 

 ii to specific gravities or atomic weights. The thermopiles 

 :;ployed were of a form slightly modified from that employed 

 y Pouillet in his demonstration of Ohm's law. Alloys are 

 lequently more powerful than elementary metals, thus : 2 parts 

 timony and i part zinc have a negative power represented by 

 70, while that of antimony is 6 96 or 9 '43, and of zinc is 

 2. A strange exception, however, is that of bismuth and tin, 

 ; while the power of bismuth is -f 35 '8, when the two metals 

 s alloyed in the proportion of 12 to i, the power becomes 

 13 '67. Dr. Stone first used a couple consisting of iron and 

 '1 German silver (that is, rich in nickel). This was charac- 

 ised by great steadiness, but the electromotive force produced 

 moderate differences of temperature was not great. He then 

 ;d Marcus's negative alloy, consisting of 12 parts antimony, 

 >f zicc, and I of bismuth, but the crystalline nature and con- 

 : |uent brittleness of this mixture were found to be great objec- 

 tions to its practical use. It occurred to Dr. Stone that the 

 addition of arsenic might diminish the brittleness without injur- 

 :^ the thermo-electric power, and on trial it was found that an 

 jy of zinc, antimony, and arsenic, with a little tin, formed a 

 .iiuch less brittle mass than Marcus metal, with quite as great or 

 j greater thermo-electric power. A set of twelve couples of this 

 alloy and German silver was exhibited . The electromotive forces 

 of this set and of a similar one of twelve iron and German .sUver 

 couples were determined by Mr. W. J. Wdson, and found to be, 

 r one aUoy and German silver couple with difference of tem- 

 -rature of 80° C,, -^\^ of a Daniell's cell. The electromotive 

 roe of one couple of the iron and German silver set was -^ 

 a Daniell's cell. The ordinary method of applying heat by 

 trough of hot water is objectionable, for the water short-circuits 

 some of the current. This is evident from the fact that if oil 

 heated to the same temperature be substituted, a considerably 

 "eater deflection is obtained. Another method suggested by 

 • e author, which would tend to economy, is to allow petroleum 

 J volatilise in jhe neighbourhood of one face of the pile, thus 

 chilling it, and to ignite the mixture of air and gas so prcKluced 

 at the other face. Clamond's pUe, consisting of iron and an 



alloy of zinc and antimony, was employed for some time, but 

 although good results were obtained, the iron is liable to rust at 

 the connections. — Dr. Guthrie remarked that in researches of 

 this nature the main object in view was to ascertain what rela- 

 tion, if any, existed between the direction of the current and the 

 amount of heat-flow. He referred to the experiment with a tangle 

 of fine platinum wire, by which it is found that if either end of the 

 wire be heated, a current flows towards the tangle, and this 

 takes place however well the tangle may be annealed. Dr. 

 Guthrie suggested that the great effect which alloyirg one metal 

 slightly with another has on its position in the thermo-electric 

 senes may perhaps be connected with its change in conducting 

 power for heat. — Mr. Walenn referred to expeiiments which he 

 made some years since on thermopiles when u>ed at high tempera- 

 tures. The mo5t powerful currents were obtained with a couple in 

 which amalgamated copper was employed, but the power was 

 soon lost in consequence of the volatilisation of the mercury. 

 Subsequently he employed wiresof wrought iron and Germansiiver, 

 and although the results were not specially remarkable at mode- 

 rately high temperatures, the power became great when the connec- 

 tions were raised to a red heat. — Prof. Foster called attention to 

 Matthiessen's table of the electric conductivities of metals and 

 alloys in relation to the use of the latter in thermopiles. The 

 fact shown by Matthiessen that the conductivities of alloys are 

 grea'ly influenced by changes of temperature, will probably, he 

 considers, be found to have some connection with their thermo- 

 electric action. He also mentioned, as a fact which should be 

 remembered when considering the construction of thermopiles, 

 that the presence of minute traces of impurity completely changes 

 the electric conductivity of a metal. 



Anthropological Institute, Nov. 9. — Col. A. Lane-Fox, 

 president, in the chair. — Major T. F.Wisden was elected a mem- 

 ber. — Mr. Francis Galton, F.R. S., read the following papers : — 

 " Heredity in Twins." On comparing the number of twins found 

 among the uncles and aunts of twins with those found in similar 

 classes of society generally, it appears that twin-bearing is 

 hereditary, in so far that there is an excess per cent, of three 

 individuals of twin birth in the former group. It further appears 

 that the male and female lines contribute the twin-bearing ten- 

 dency in identical proportions. The families are very large in 

 which twins are born ; even those of their parents average nearly 

 seven persons, but the twins themselves appear neither to marrj' so 

 frequently nor to be so prolific as other persons. However, the 

 common belief that both twins are in no case ferdle is quite 

 untrue. — " A Theory of Heredity." Starting with the generally 

 admitted view that the body consists of a multitude of organic 

 units, each of which is to a certain degree independent of the 

 rest, and with certain postulates which that view implicitly 

 recognises, there exists a firm basis on which to establish a theory 

 of heredity. By these and their necessary consequences, the 

 object of double parentage, and therefore of sex, was first ex- 

 plained by the likeness and dissimilarities observed between 

 brothers and sisters, and the still more remarkable similarities 

 and contrasts between twins of the same sex, were then ac- 

 counted for. It was argued that the germs which were selected 

 for development into the bodily structure had very small influ- 

 ence in an hereditary point of view, but it was those germs that 

 were never developed but remained latent, that were the real 

 origin of the sexual element ; by this hypothesis the almost com- 

 plete non-transmission of acquired modification was explained ; 

 also the occasional fact that strongly marked characteristics in 

 the parents were sometimes barely transmissible, and again that 

 of certain diseases skipping alternate generations. It vias further 

 supposed, in the successive s^regations and segmentations of the 

 earliest germinal matter, that the divisions w ere never precise, 

 and therefore that alien germs were ultimately included in each 

 structure j thus latent germs of all kinds became distributed over 

 all parts of the body. This accounted for much that Mr. 

 Darwin's theory of Pangenesis over-accounted for, and was free 

 frtm objections raised against the latter. The assumed evidence 

 that structural changes under modified conditions of life reacted 

 on the sexual elements was then discussed, and it was pointed 

 out that much that had the appearance of heredity was not so in 

 fact, but was due to changes of the sexual elements collaterally 

 with the structural ones. A modification of Pangenesis was 

 adopted, as a subsidiary part of the main theory, to account for 

 the occasional and limited transmission of acquired modification. 

 The precise character of the relationship that connects the off- 

 spring with the parents was then defined. — Mr. F. W. Rudler, 

 F.G. S., read a report on the Department of Anthropology at 

 the Bristol meeting of the British Association. 



