August 6, 1896J 



NA rURE 



335 



and then bring about the freezing of the water by dropping in a 

 crystal of ice. The thermometer then rises, and finally attains 

 a steady temperature, differing only very slightly from the true 

 zero. 



The apparatus employed consists of two portions, the 

 thermostat and the cooler. The former is a copper vessel, 

 filled with either refined petroleum or a strong solution of 

 common salt. This vessel communicates with the cooler, 

 through which the liquid can be pumped by a rotary stirrer ; and 

 by this means it can be cooled and maintained for some time at 

 about -2'. The distilled water to be frozen is contained in a 

 glass tube of about 300 c.c. capacity. This is first placed 

 directly into the circulating liquid, and cooled quickly to 

 -0"5' or -07 . It is then transferred to a cylinder lined with 

 polished metal, pl.iced in the centre of the thermostat. The 

 thermometer who.se zero is to be taken is then quickly fixed in 

 position, the bulb and a considerable length of the stem above 

 the zero being immersed in the water. A crystal of ice is 

 dropped in, and the temjierature quickly rises to the freezing 

 point. 



Experiments made with good mercurial thermometers showed 

 that if ice be present in sufficient quantity, the final temperature 

 attained by the mixture of ice and water is not influenced 

 perceptibly by variation of the temperature of the circulating 

 liquid within fairly wide limits. As, however, it seemed 

 desirable to control this result by .some other means, a platinum 

 thermometer and bridge were designed, capable of indicating 

 with certainty a change of O'oooi", and a description of the 

 whole arrangement employed to attain this degree of accuracy 

 forms the second half of the paper. The resistances in the 

 bridge were of manganin, and the thermometers were provided 

 with tlie compensating leads, devi.sed by Mr. Callendar. The 

 maximum current wliich can be used in accurate measurements 

 with these thermometers is about o"02 ampere, and therefore 

 the galvanometer employed required to be extremely sensitive. 

 The instrument selected was a low resistance astatic one with 

 vertical needle system, and gives at the greatest working 

 sensibility one .scale division for I x 10'"' ampere. 



With this arrangement the influence of various conditions on 

 the final temperature attained by the mixture of ice and water 

 was studied, The results were found to be in close agreement 

 w'th the theoretical deductions of Xernst, and it was quite easy 

 til keep the temperature in the freezing vessel constant to 

 within one or two ten-thousandths of a degree for an hour at 

 a time. 



The conclusion drawn from the pre\ ious experiments made 

 with mercurial thermometers as to the small influence of 

 changes in the external temperature, and in the temperature of 

 the circulating liquid on that of the freezing vessel, was also 

 confirmed, and it was found that a change of two or three 

 degrees in the temperature of the circulating liquid only caused 

 the temperature of the mixture in the tube to alter by three or 

 four ten-thousandths. 



ElUNHfRC.H. 



Royal Society, fuly 20.— The Hon. Lord M'Laren in the 

 chair. — I'rof. Tait gave a brief description of a paper by Lord 

 Kelvin on the different configurations possible with the same 

 law of force according to Boscovich. In previous papers the 

 author had confined him.self to a treatment of the nature of con- 

 figuration. This paper was a daring application of principle 

 towards a rational explanation of crystalline form, having regard 

 to the mutual forces involved. — Prof. Ludwig Boltzmann's com- 

 munication, read by Prof. Tait, on the importance of Clerk- 

 Maxwell's contributions to the kinetic theory of gases, consisted 

 of a few sentences setting forth the writer's high respect for 

 Clerk-Maxwell, and defining his relations with M. Bertrand. 

 The paper in full was promised later. — Dr. Halm read an 

 abstract of his paper on theoretical researches on the daily change 

 of the temperature of the air. The fundamental differential 

 equations of the problem, so far as they concern the curve of 

 temperature during night, were first propounded by A. Weilen- 

 mann, in his essay, " Ueber den taeglichen Gang der Temperatur 

 zu Bern" {St/nveizerisihc' Metcorol., Beobachtungen ix. , 1872), 

 which may be considered as the first successful attempt at in- 

 vestigating the question from a theoretical point of view. But 

 the physical explanation of his mathematical terms being in- 

 sufficient, the author undertakes to show that these equations 

 are in perfect agreement with the fundamental laws of radiation 

 and conduction of heat, as given by Fourier and many others. 

 The general question, by what means does the lowest layer of the 



NO. 1397, VOL. 54] 



atmosphere, the temperature of which is recorded by our 

 thermometric instruments, receive or lose heat, may be 

 answered by this result. Every change of temperature is 

 caused by continuous radiation between the soil and an un- 

 known part of the atmosphere — for which, however, there can 

 be substituted, under all circumstances, two masses of air with 

 the same coefficient of radiation, one of these having the variable 

 temperature of the observed lowest layer ; the other, a constant 

 temperature. The next part of the paper consisted in proving 

 that Weilenmann's equations, by a proper application of the 

 sun's radiating power at every moment during the day, can be 

 used for deriving an integral which gives expression to the 

 change of the temperature during the time from sunrise to sun- 

 set. This integral consists of two different parts, one of which 

 contains two arbitrary constants, naturally involved by the pro- 

 cess of integration ; the others are functions of time introduced 

 by the law of solar radiation on a horizontal surface. But it can 

 easily be proved that both the arbitrary constants have to dis- 

 appear in every case, so that the change of temperature appears 

 to be regulated simply by functions directly depending on the 

 radiating power of the sun. Considering the fact that the con- 

 ditions of radiation must be importantly influenced by various 

 systematical disturbances, such as convection currents, the con- 

 tinuous change of the quantity and quality of atmospheric 

 moisture, the state of cloudiness and the physical conditions of 

 the soil, great importance has to be laid on the question how 

 these may be given expression to in the fundamental equations 

 of the problem. As far as the convection currents are con- 

 cerned, their influence is shown to be in perfect agreement with 

 observations, the range of temperature being diminished, and 

 the time of maximum being brought nearer to the culmination of 

 the sun when the direction of the current is from a cold quarter ; 

 the opposite being the case when from a warm one. The effect 

 of sea-breezes is an example of the former condition ; that of 

 currents flowing from a mountain to the valley during daytime, 

 an example of the latter. The very considerable effect of the 

 daily change in the amount of atmospheric moisture, which has 

 been deduced from direct observation of clouds and the absolute 

 humidity of the air, complicates the theoretical equation by add- 

 ing a new term, the parameters of which can be shown to be in 

 full agreement with these observations. The most important 

 branch of the subject treated in the paper was the determination 

 of the solar constant from the daily temperature observations, 

 which, after the influence of the state of cloudiness and the 

 change of the physical conditions of the soil therefrom resulting, 

 have been investigated, show values sufficiently accurate to 

 admit of examining the question of the periodicity of solar radia- 

 tion by a method the advantages of which seem cjbvious com- 

 pared with the commonly used method founded on study of 

 mean annual temperatures. From a large number of stations 

 in Austria and Hungary, whose observations, extending over 

 the years 1876-93, have been used, the author shows a close 

 correspondence between the inverted curve of sun-spots and 

 that of solar radiation. A much fuller investigation, however, 

 extending over a longer series of years, and embracing a greater 

 extent of territory, is required to finally establish the results 

 deduced. — Prof J. M. Dixon, of St. Louis, described in an in- 

 teresting and popular manner the tornado which recently visited 

 that city, and of which he was an eye-witness. The report 

 already given in N.A.TURE (vol. liv. p. 104) he characterised as 

 correct. — Mr. Robert Kidstou read a paper describing some 

 cones o{ Sigi/lartl, in which the structure of the sporangia was 

 shown. The sporangia appeared to be immersed in the bracts 

 in a somewhat similar manner to that which occurs in Isoetes 

 showing that the affinities of Sigillarii are with /soe/es, as con- 

 jectured by Goldenberg. Two new species of Sigillarian cones 

 (Sigillariostrobiis) were described, and a new species oiSigillaria. 

 — Prof.Charteris read a short paper on the physiological action of 

 eucaine. He claimed for this new antiseptic, which he described 

 merely as a compound synthetically prepared, that it was not 

 so toxic as cocaine, while the anaesthesia it produced was as 

 complete. It did not contract the pupil when applied to the 

 eye, and a solution in water did not decompose. — The Chairman, 

 in a few words, reviewed the work of the past session, and held 

 out hopes of further prosperity and usefulness in the future. 



Paris 



Academy of Sciences, July 27.— M. A. Cornu in the 



chair.— On the water-spout of July 26, at the Museum 



of Natural History, by M. Milne-Edwards. An account 



