April 27, 1876] 



NATURE 



533 



currents seemed to him to point to a reason for the existence of 

 a warm region, like that which Herr Hann found for the high 

 temperature of the Fohn wind, namely, that in descending the 

 cold air becomes condensed, and by condensation raised in tem- 

 perature. From 4 P.M. on the 4th to 5 p.m. on the 5th of 

 November, 1S74, readings of the temperature were taken by four 

 observers at Innsbriick (575 metres), Rumer Alpe (southern 

 slope, 1,227 metres), Heiligwasser (northern slope, 1,239 metie-), 

 and at the summit of the I51a;er (2,240 metres). The mean 

 temperatures for the twenty-four hours at these stations were 

 respectively, 2"i6, 7-06, 4'26, and — 64. The lowest ni^ht 

 temperature at Innsbriick was — 28; on the Rumer Alpe, 

 4- 2'4. The mmimum was reached at Innsbriick, just before 

 sunrise, but on the Rumer Alpe at 3.30 A.M. ; at sunrise at this 

 ■evation the thermometer marked 4'4. At Heiligwasser the 

 .line kind of relation was noted, and temperature rose after 

 4 .^.M. ; but the maximum by day was much lower than at Inns- 

 briick. The high temperature at this station was not due to 

 heating of the ground by sunshine, for a thermometer fixed on 

 the surface of the soil never rose above 1° C. The wind blew 

 uninterruptedly towards the valley, down the mountain side. 

 There remains but one explanation, namely, that the increasing 

 pressure raises the temperature of the air as it descends. Prof. 

 Kemer proceeds to a more detailed analysis of the distribution 

 of currents over hill and valley both by day and by night, illus- 

 trating his theoiy by diagrams. After sunset the ground of the 

 valley and the a'r above it cool rapidly by radiation. The air 

 thus made specifically heavy cannot flow off, but n sis like a lake 

 at the bottom of the valley. The current which has flowed 

 down the mountain sides being raised in temperature, glides over 

 this stratum, and rises about the middle of the valley, to rejoin 

 the polar wind aloft. By day the air ascencs from the valley up 

 the southern slope, and is replaced by a current descending the 

 opposite mountain face. Obviou-'^ly, the phenomenon of in- 

 creasing temperature with increasing height must be most strik- 

 ing where the ridges and valleys stretch from west to east, and 

 during periods of polar wind, when the sky is clear and radiation 

 strong. 



Der Nattirforscher, January. — This number contains an ac- 

 count of observations by M. von Schleinitz, on board the 

 Gazelle, when on the transit expedition to Kerguelen's Land, of 

 changes of temperature and specific gravity of water in the 

 southern Indian Ocean. His conclusions are brieily these : — I. 

 Ocean currents, with the exception of the currents caused by re- 

 gular winds, are due to differences in absolute specific gravity of 

 diff-erent parts of oceans, and a small difference produces a strong 

 current. 2. The differences in saltness of tropical and cold seas 

 (in relation to absolute specific gravity), acting oppositely to the 

 temperature differences, moderates ocean currents, which would 

 otherwise be so strong in meridional directions that navi- 

 gation would be impossible. 3. There is probably a zone where 

 the differences in saltness compensate the differences in tempera- 

 ture, so that waters of diff^erent temperature and different salt- 

 ness may be near each other in equilibrium, i.e., without percep- 

 tible current. In the western part of the Indian Ocean this 

 zone is between 40* and 45" S. lat. — There is a notice of two 

 recent series of researches by M. Voigt and M. Groth (conducted 

 by quite different methods), on the elasticity of rock salt ; it is 

 shown that in regular crystals the co-efficient of elasticity, and 

 therewith the velocity of sound, is a function of the direction ; 

 and that both vary, in accordemce with Neumann's theory, sym- 

 metrically with reference to the planes of symmetry of the 

 crystal. — M. Frank calls attention to the action of light on the 

 opening of some catkin-like blossoms. — From experiments by 

 M. LuchsinL;er, it appears that glycerine injected under the skin 

 of animals lias an arresting action on the fermentative formation 

 of sugar from the glycogen of the liver. — The remaining papers 

 do not call for notice here. 



Jahrbiicher fiir Wissenschafiizcne Botanik. Herausgegeben yon 

 Dr. N. Pringsheim. Zehnter Band, Drittes Heft, Mit. 11, 

 Tafeln (Leipzig : Verlag von Wilh. Engelmann, 1876). — The 

 present number of Pringsheim's well-known " Year-book" con- 

 tains three papers, all ot great value. The first is by Dr. George 

 Winter, on the genus Sptweromphale and its allies (with three 

 plates). Koerber in criticising the Schwendener-Bornet theory 

 of lichens, stated that Sphteromphalc had only greenish-brown 

 microgonidia, and that the !■ pores did not produce hyphse. Both 

 these statements are shown to be erroneous, and after a careful 

 anatomical and morphological examination of numerous original 

 specimens, dried and recent, of Sphreromphale and its allies, he 



groups them together under a single species, Polyblastia umbrhia 

 (VVhlnbg.), Winter, and adds nearly three pages of synonyms ! — 

 an eloquent tribute to the species-making capabilities of modern 

 Lichenographers. — The second paper is by Dr. A. Engler, Con- 

 tributions to the knowledge of the formation of the anther in 

 Mctasperras. This paper, which is illustrated with five plates, 

 describes the following subjects : (i) the anthers and pollen of 

 the Mimoseai ; (2) the anthers of Orchidacete ; (3) the anthers 

 of AsclepiadaceK ; (4) on the so-called introrse and extrorse 

 anthers ; (5) on certain apparent departures from the type in the 

 formation of stamens; and (6) on the homologies between stamen 

 and carpel. — The third paper is by Dr. J. Reinke, Contributions 

 to the knowledge of Fucace^e and Laminariae (with three plate*). 

 The anatomy and external construction of several genera and 

 species are detailed, the most interesting portion of the paper 

 beiiig the paragraphs devoted to secondary circumferential growth 

 in f ucacea;, and to the formation of adventitious buds. — The 

 illustrations are excellent as usual, and the high character of the 

 yahrbiiclier well sustained. 



Bulletin de VAcademie Royal des Sciences, Nos. 9 and 10, con- 

 tains an article by Van Beneden on the Pachyacanthus in the 

 Museum at Vienna. The description of other marine mamifers 

 in other museums is to follow, and the whole are to form an 

 introduction to the descriptions of the allied fossil forms dis- 

 covered in excavations near Antwerp. 



SOCIETIES AND ACADEMIES 

 London 



Royal Society, April 6. — "Experiments on the Friction 

 between Water and Air." By Dr. Ritter von Lang. Com- 

 municated by N. Story Maskelyne, F".R.S., Keeper of the 

 Mineral Department, British Museum. 



The method adopted for estimating the mutual friction of 

 water and air consisted in connecting a glass tube of 8 centims. 

 in length and 072 internal diameter with the pipes which supply 

 Vienna with water at a pressure of four atmospheres. Arrange- 

 ments for securing a vertical position for the tube ensure a 

 perfectly continuous jet, devoid of any broken surface ; and a 

 tube surrounding this jet, with its axis coinciding with that of 

 the jet, acts as an aspirator into and along which air is drawn 

 through a lateral feeding-tube. The amount of this in-drawn 

 air corresponding to the fall of a given amount of water was 

 determined by observing the rate at which a film of soap was 

 borne along the feeding-tube ; and the velocity of the water 

 causing the in-draught was calculated from the diameter of the 

 water-column and ihe quantity of water discharged along it in 

 a given time ; but after having once determined the form of the 

 slightly conical water column, the amount of water discharged 

 was the only datum required for the calculation. 



The influence of a greater or less section of the air feeding- 

 tube on the volume of the aspirated air was carefully deter- 

 mined, while also the absence of any appreciable retardation 

 due to the soap- film was established. 



Neglecting the slightly conical character of the surface of the 

 water-column, and assuming (as the result of experiments in 

 which the motion of a smoke-cloud was observed) that the 

 movement of the air was throughout in lines parallel to the axis 

 of the tube along which it flowed, and showing that the pres- 

 sure does not vary along the length of the tube, the author pro- 

 ceeds to discuss the hydrodynamic equations expressing the con- 

 ditions of the problem (the motion of the air being uniform and 

 independent of time), and represents the volume of air A passing 

 through the tube in a second as 



A=wr -,^„-4- -il, 



L2/-'(log R — log r) J 



W^ being the we'ght of water, in grammes, discharged in a 

 second, r the radius of the jet in turns of the micrometer-screw 

 (6"8 turns of which correspond to I centim.), R being the radius 

 of the aspirating tube. 



The results obtained by observation accorded well with those 

 given by this equation, so long as the value of R did no: exceed 

 tfie limit within which the suppositions regarding the motion of 

 the air hold good. 



The question whether the results might not be brought into 

 even closer accord with theory by the assumption that a slipping 

 action takes place between the air and the water-jet on the 

 one band, and between the air and the tube on the other, 

 instead of the assumption previously made that the air adhtred 



