398 



NATURE 



[March i8, 1875 



summer a black bulb theimometer was exposed to the rays of the 

 sun ; during the winter frequent observations were made with 

 exposed and covered minimum thermometers to ascertain the 

 nightly radiation at low temperatures. In both winters February 

 was the coldest month, while January both times showed a rise 

 in the temperature when compared either witli December or 

 February. In winter the temperature was highly variable, and 

 sudden rises or falls were frequent ; in the three summer months, 

 however, the temperature was very constant, and changes very 

 rare. July was the warmest month. The lowest reading was 

 - 374" R- (nearly - 47° C.) The influence of extremely low 

 temperatures upon the human body has often been exaggerated ; 

 there are tales of difliculty in breathing, pains in the breast, &c., 

 that are caused by them. Lieut. Weyprecht and his party did 

 not notice anything of the kind ; and although many of them 

 had been born in southern climes, they all bore the cold very 

 easily indeed ; there were sailors amongst them who never had 

 fur coats on their bodies. Even in the greatest cold they all 

 smoked their cigars in the open air. The cold only gets unbear- 

 able when wind is united to it, and this always raises the tempe- 

 rature. Altogether, the impression cold makes upon the body 

 differs widely according to personal disposition and the quantity 

 of moisture contained in the air ; the same degree of frost pro- 

 duces a very uncomfortable effect at one time, while at another 

 one does not feel it. 



To determine the quantity of moisture in the atmosphere, an 

 ordinary psychrometer, a dry and a wet thermometer, were used. 

 But the observations with these instruments are not reliable at 

 low temperatures, and had to be given up altogether during 

 winter, as the smallest errors give great differences in the abso- 

 lute quantity of moisture in the air. In order to deteimine 

 approximately the evaporation of ice during winter, Lieut. 

 \Veyprecht exposed cubes of ice that had been carefully weighed 

 to the open air, and determined the loss of their weight every 

 fourteen days. 



[To be continued^ 



PRIZES OFFERED BY THE BELGIAN 

 ACADEMY 



THE following subjects for prizes to be awarded in l866 have 

 been proposed by the Royal Academy of iSciences, 

 Belgium : — 



1. To improve in some important point, either in its prin- 

 ciples or applications, the theory of the functions of imaginary 

 variables. 



2. A complete discussion of the question of the temperature 

 of space, bated upon experiments, olJservations, and calculation, 

 stating the grounds for the choice made between the different 

 temperatures attributed to it. 



Competitors should obsei-ve that the above question, stated in 

 the most general terms, is connected with the knowledge of the 

 absolute zero, definitely fixed at -272° '85 C, but that a histori- 

 cal and analytical inquiry into researches undertaken, previous 

 to about 1S20, to resolve this question, would offer a real 

 scientific interest. Particular attention is called to the works of the 

 end of the eighteenth ceni ury and the commencement of the nine- 

 teenth ; among others, those of Black, Irvine, Crawford, Gadohn, 

 Kirwan, Lavoisier, Lavoisier and Laplace, Dalton, Desoimes 

 and Clement, Gay-Lussac, &c. Note also the temperature, 

 — l6o°C., which Person indicates; according to his formula, 

 which connects the latent heat of fusion with specific heats, this 

 number would represent the absolute zero. As it comes near to 

 that given by Pouillet, it will be important to discover what is 

 its signification, its import {sens), or its exact physical value. 



3. A complete study, theoretical and, if necessary, experi- 

 mental, of the specific absolute heat of simple and of compound 

 bodies. 



4. New experiments on uric acid and its derivatives, chiefly 

 from the point of view of theur chemical structure and their 

 syntheses. 



5. New researches into the formation, the constitution, and 

 the composition of chlorophyll, and into the physiological role of 

 that substance. 



6. To expoimd the comparative anatomy of the urinary appa- 

 ratus in the vertebrates, basing it on new organogenic and histo- 

 logical researches. 



The prize for the first, the fourth, and the sLxth questions will 

 be a gold medal of the value of 800 francs, the prize for the fifth 



will be of the value of 600 francs, and the prize for the second 

 and third questions will be of the value of 1,000 francs. 



The memoirs must be legibly written, either in French, . 

 Flemish, or Latin. They should be addressed, carriage-paid, to- 

 JI. J. Liagre, Perpetual Secretary of the Academy, at the 

 Museum, before August 1876 ; any received after which will be 

 out of the competition. 



Authors must not put their names to their works. Oiily a 

 motto must be attached, and the same written outside an enve- 

 lope enclosing the author's name and address. This condition 

 is indispensable. 



SOCIETIES AND ACADEMIES 



London 



Mathematical Society, March ii.^Prof H. J. S. Smith, 

 F.K.S., president, in the chair. — Mr. Roberts gave an account 

 of his paper on a simplified method of obtaining the order of 

 algebraical conditions. — Prof Sylvester, F. R. S., then spoke on 

 "an orthogonal web of jointed rods, a mechanical paradox.' If 

 two sels of points be taken respectively in two lines perpendicular 

 to each other, either in a plane or in space, and a linkage be 

 formed by connecting each point in one set with each point in 

 the other by jointed rods, this constitutes what the author means 

 by an orthogonal web. It is not a fixture, and its motion is 

 subject to this curious condition, that either each set of points 

 must always continue to lie in the same right line, which may be 

 called a neutral position, or else one set will lie in a right 

 line and the other in a plane at right angles to such line. 

 Starting from the neutral position (or position of clouhle-lock), the 

 system may be said to be subject to an optional locking about 

 one or the other of the two perpendicular lines, and an unlocking 

 about the other, but when once put in motion the system must 

 be again brought into the same or a new neutral position before 

 the one axis of lock can be got rid of, and another at right angles 

 thereto substituted in its stead. If the whole motion be confined 

 to a plane, the paradox consists in the link combination possessing 

 one degiee of liberty of deformation (aAAoiaxris as distniguished 

 after Plato from Kij-Tjo-ts), although a calculation of the amount 

 of restraint by the general method applicable to such questions 

 would seem to indicate that it ought to form an absolutely rigid 

 system except in the case where there are only two joints in one 

 at least of the two sets. Taken in space there is the further and 

 more striking paradox that the number of degrees of liberty of 

 deformation according to the choice made of one or the other of 

 the two sets of points to be unlocked out of the rectilinear into 

 the planar position will be the alternalhe of two numbers, viz. 

 the number of joints in the one set or in the other set (which 

 need not be the same), a kind of indeterminaleness in the " index 

 of freedom" without precedent in kinematical speculations. As 

 lightning clears the air of impalpable noxious vapours, so an 

 incisive paradox frees the human intelligence from the lethargic 

 influence of latent and unsuspected erroneous assumptions. 

 Paradox is the slayer of prejudice. — The Secretary, in the author's 

 absence, then lead a portion of Mr. G. H. Darwin's paper on 

 some proposed forms of shde-rule. The object of the author 

 was to devise a form of slide-rule which should be small enough 

 for the pocket and yet be a powerful instrument. The first 

 proposed form was to have a pair of watch-spring tapes 

 graduated logarithmically, and coiled on spring bobbins side by 

 side. There was to be an arrangement for clipping the tapes 

 together, and unwinding them simultaneously. Two modifica- 

 tions of this kind were given. The second form \\as explained 

 as the logarithmic graduation of several coils of a helix engraved 

 on a brass cylinder. On the brass cylinder was to fit a glass one, 

 similarly graduated. To avoid the parallax due to the elevation 

 of the glass above the other scale, the author proposed that the 

 glass cylinder might be replaced by a metal corkscrew sliding 

 in a deep worm, by which means the two scales might be brought 

 flush with one another. 



Anthropological Institute, March 9. — Col. A. Lane Fox, 

 president, in the chair. — Sir Duncan Gibb read a paper on 

 Ultra Centenarian Longevity, in which he exhibited some tables 

 giving eighty-four instances of the reputed age of 107 to 175 

 years, a certain proportion of which he considered he had 

 grounds to believe to be correct. Of nine living centenarians 

 whom he had previously examined for physiological purposes, he 

 now added a tenth — the Tring centenarian — who died recently 

 in her I I2th year. The correctness of her age was^ considered 



