July i i, 1901] 



NATURE 



263 



season (January and February only) 4100 feet, the velocities being 

 respectively 137 and I0'2 miles per hour. The maximum 

 velocity of the cirrus was estimated at 282 miles per hour both 

 in February and March. 



An interesting letter by L. Schafli on approximate integra- 

 tion is reproduced by lierr J. H. Graf in the Berner Milthei- 

 iuiigen for 1899, recently sent to us. The letter was written to 

 a friend in explanation of certain difficulties he had experienced 

 in reading Raabe's books on the calculus, and it probably 

 •dates from about 1S40. It appears to throw some new light on 

 the history of Bernouilli's numbers and functions, besides 

 affording evidence of Schafli's great power as a mathematician. 



In the Journal de Pkyshpie for May, M. Bernard Brunhes 

 writes on the entropy of a gaseous mixture in combustion. It 

 has been hitherto regarded as an objection to the use of entropy 

 diagrams that they could not be used in connection with gas an J 

 oil engines, on account of the essentially irreversible nature of 

 the explosions and the consequent uncertainty as to whether 

 the entropy of the mixture was calculable or could even be said 

 to exist. M. Brunhes now shows that, under certain well-defined 

 conditions, the entropy is both determinate and calculable. 



Prof. Oreste Murani points out in the Lombardy Rendi- 

 coiiti that a focus-tube at a certain degree of vacuum acts like an 

 " electric valve " for alternating currents, in that it allows the 

 current to pass in one direction but 'not in the other. The 

 notion of an electric valve appears to have been originally 

 due to Gaugain, and it has been known that a Geissler's tube 

 in which the electrodes have different forms may act in this 

 way. In the case of a focus-tube there appears to be a superior 

 and an inferior limit to the degree of exhaustion at which it acts 

 in this manner, the superior limit corresponding to a pressure 

 of about O'l mm. of mercury, and the inferior limit, which has 

 not been determined with such certainty, corresponding to 

 0"07 mm. Prof. Murani considers that a focus-tube may be 

 used to indicate the sense of la discharge in certain cases where 

 a more direct method is inapplicable ; it might be also used to 

 convert an alternating current into a direct one, but the intensity 

 of the latter would be very small. 



The monaural localisation of sound receives treatment at the 

 hands of Prof. James Rowland Argell and Dr. Warner File in 

 the Psychological Review for May. The paper reports a series 

 of observations on the capacities of auditory localisation in a 

 person entirely deaf in one ear, but parallel observations have 

 in certain cases been made upon a person of normal hearing. 

 So far as it is possible to briefly give some idea of the con- 

 clusions, it is shown firstly that the differences in the localising 

 capacity for complex sounds in binaural and monaural hearing 

 are, so far as concerns these subjects, interpretable as chiefly 

 differences in the magnitude of the ^difference limen for locality 

 rather than as absolute differences in the kind of localising 

 process involved. The experiments amply sustain the intro- 

 spection of the subject in pointing to qualitative difterences in 

 the sounds coming from difterent directions as the basis of the 

 localisations. Such qualitative differences may be due to 

 the damping or reinforcing of certain partial tones by the 

 organs of the ear and the head, and it is noteworthy that 

 generally sure tones are unlocalisable in monaural hearing. The 

 presence of eye-reflexes was often very marked, and the final 

 localisation was frequently made on the basis of a seeming 

 correspondence between the eye-strains and the supposed 

 direction of the sound. This statement, however, leaves un- 

 touched the physiological basis of the eye-movements. Finally, 

 there is no good evidence for supposing that cutaneous sensa- 

 tions play any part in the localisations. 

 XO. 1654, VOL. 64] 



The thermal conductivity of the living human skin forms the 

 subject of an investigation by Mr. J. Lefevre in the_/«(/'«a/a'e- 

 Pliysique for June. Regarding the skin as a wall about 2 mm. 

 thick, three coefficients have to be found, namely, the surface 

 conductivity, the true conductivity through the substance form- 

 ing the skin, and the internal surface conductivity between the 

 skin and the adjoining tissues. To find these it was necessary 

 to determine the rate of flow of heat across a unit area of the 

 skin, and to measure the distribution of temperature from the 

 surface downwards. For the former purpose M. Lefevre im- 

 mersed himself in a bath of water which served as a calorimeter, 

 for the second he used thermoelectric elements, that used for 

 subcutaneous observations taking the form of a fine needle. 

 The experiments show that the skin is a bad conductor, its true 

 conductivity being about the same as that of wood, of the same 

 order as that of gutta percha, about 5 or 6 times that of wool 

 and 750 times that of air. The conductivity is only half as great 

 at 5° as at 30° C. The exterior surface-conductivity of the skin 

 in contact with water appears to be approximately independent 

 of the temperature, but the coefficient across the surface 

 separating the skin from the adjoining tissues increases con- 

 siderably as the temperature falls from 30' to 5°, and the latter 

 increase more than counterbalances the decrease in the true 

 conductivity, so that the loss of heat at 5° C. is twice or thrice as 

 great as it would be according to Newton's law. 



The new number of the Mitlheilmigeit of the \'ienna Geo- 

 graphical Society contains two papers of interest. Herr H. 

 Anschutz-Kaempfe describes a plan for exploring the Arctic 

 Ocean and reaching the North Pole by means of a submarine 

 vessel. Herr V. von Lozii'iski treats of chemical denudation in 

 relation to geological time, and gives a valuable summary of 

 recent work bearing on this subject. The calculations of Mr. 

 Mellard Reade and von Romer are specially dealt with, and the 

 latter are repeated, with modifications, employing the most 

 recent data of Murray, GUmbel and others. 



Dr. G. Schott gives, in the Verhandlungen der Gesell- 

 schaft fiir Erdkuiide zii Berlin, an interesting forecast of some 

 of the oceanographical results of the Valaivia Expedition, the 

 full report on which may be expected next winter. The 

 Valdivia observations have been combine d with older material 

 so as to bring maps of distribution of temperature, as far as 

 possible, up to date, and from these Dr. Schott draws some 

 important general conclusions. In the open ocean three tem- 

 perature layers are recognised — a surface layer, o to 100 metres, 

 in which the distribution is chiefly controlled by horizontal 

 movements; a middle layer, 150 to Soo metres, controlled by 

 vertical movements ; and a bottom layer, beyond looo metres, 

 in which horizontal movements are again specially important. 

 A " Sprungschicht " occurs in every ocean, its mean depth 

 being 25 to So metres in the Atlantic, 90 to, 140 metres in the 

 Indian, and no to 180 metres in the Pacific Ocean. 



The " Karlseisfeld " was first visited by Friedrich Simony in 

 1840, and since that date almost every change in the glacier has 

 been carefully observed. Simony made his last photographic 

 survey in 1890, and since his death a survey was made, in 1896, 

 by von GroUer. The retreat of the glacier during the five years 

 following made another survey important, and this was accord- 

 ingly carried out by Freiherr von Hubl. The results are pub- 

 lished in the Abhandlungen of the \'ienna Geographical Society, 

 and, apart from their value as a study of the glacier, they form a 

 model example of the application of modern methods of photo- 

 graphic surveying to work of the kind. The account of the 

 survey forms the first of three parts of a report to be published 

 under the editorship of Herr August von Bohm ; the second 

 part is to deal with the history of the glacier, and the third 

 with its present development. In the same number of the 



