July 15, 1909] 



NATURE 



Si 



holtz, Hertz, LockytT, Kayser and Runge, Rydberg, 

 Puccianti, Stoney, and J. J. Thomson. 



In the Sitzungshcrichic of the Vienna Academy, cxvii., 

 8, g, Dr. Philipp Forchhcimer discusses certain mathe- 

 matical solutions of the problem of underground flow of 

 water in a homogeneous stratum bounded by a plane 

 impervious floor, the equation of continuity in this case 

 being the ordinary two-dimensional form of Laplace's equa- 

 tion, with the square of the depth as the dependent 

 variable. 



The theory of the polar planimcter is treated in a novel 

 way by Dr. Gabriele Torelli in the Rcndiconto of the Naples 

 Academy, xiv., 8-12 (iqoS). The author finds that the 

 treatment of the subject given in text-books is far from 

 convincing, and he proposes an alternative treatment based 

 on the use of Jacobians. Those who have worked with 

 planimetors in this country will fully agree with the author 

 as to the need of a more satisfactory investigation of their 

 principle, and if such a need exists in the case of the polar 

 planimeter it is still more necessary for the so-called 

 "hatchet planirffeter, " which is usually worked by rule, 

 with little attempt, if any, to explain its principle. 



An important contribution to our theories of wave-pro- 

 pagation in wireless telegraphy is given by Prof. A. 

 .Sommerfeld in the Annalcn dcr Physik, xxviii., pp. 

 665-736 (1909). The investigation, while taking account 

 both of surface waves and of waves distributed in space, 

 tends to support the view that we have to deal with waves 

 propagated along the surface of the earth in accounting for 

 the transmission of Marconi signals. Prof. Sommerfeld, 

 further, in his analytical results obtains analogues of 

 properties associated with electrodynamic waves in wires 

 and certain optical phenomena (Brewster's law). 



In the Rassegna conicmporanea for May, 1908, Mr. Gino 

 Cuchetti discusses the project for anti-seismic houses, due 

 to Prof. Giuseppe Torres, of Venice. This project is based 

 on the view that circular structures are the best calculated 

 to withstand earthquake shocks, and in the designs shown 

 in the illustrations each building consists of several circular 

 turrets of different diameter communicating with each 

 other, an arrangement having considerable artistic merits, 

 though wasteful of space. In the succeeding number of the 

 Rassegna Dr. Enrico Panlano discusses the problem of 

 " internal colonisation " as applied to Italy, and we note 

 with considerable interest the important bearing on this 

 problem of the campaign against malaria. 



A Riii'ORT on the resistance of rivets is presented by 

 M. Ch. Fremont to the Bulletin de la Societe d'Encourage- 

 ment for April. It is pointed out that the resistance of 

 riveted plates to statical force.5 or shocks should be borne 

 as much as possible by the adhesion of the plates and as 

 little as possible by shearing of the rivets themselves, and 

 the author emphasises the necessity of standardising the 

 heads of rivets and of regulating the maximum tempera- 

 ture during the process of heating, so as not to destroy 

 the elastic qualities of the rivet. The increased efficiency 

 obtained by tlie application of continued pressure during the 

 riveting is also mentioned. 



In a paper on the most general problem of uptics, pub- 

 lished in the Proceedings of the Turin .Academy of Sciences, 

 Prof. Antonio Garbasso and Guido Fubini point out that 

 little has been done in solving problems of propagation 

 of light waves in a medium which is neither homo- 

 geneous nor isotropic. The authors propose a theory for 

 the special case of a medium in which the ellipsoids of 

 elasticity are of revolution having their axes parallel, and 

 the lengths of these axes are the same at all points in a 

 plane perpendicular to the axis of revolution- An illustra- 

 NO. 2072, VOL. 81J 



lion of such a medium is afforded by a stratum of gelatirf. 

 placed in contact with a solution of zinc chloride and sub- 

 jected to pressure ; the colours seen in such a rnedium under 

 polarised light are shown in a plate accompanying the- 

 paper. 



We have received part iii. of " Klimatographie von. 

 Oesterreich," issued by the Meteorological Office of Vienna, 

 in which the climatology of Styria is fully and ably dis- 

 cussed by Dr. Robert Klein. The treatment of the subject 

 follows closely along the lines laid down by Hann in his 

 " Handbuch der Klimatologie, " and is, indeed, similar to 

 that adopted by that author in the earlier parts of the 

 work which deal with Austria proper. The book is a 

 model of what the treatment of the special climatology 

 of a restricted area should be. It gives for each region 

 the probabilities of the occurrence of phenomena such as 

 frosts of different degrees of intensity, heavy rainfall, and 

 others. At the same time, the underlying principles are 

 not lost sight of. Styria presents many features of special 

 interest, as the altitudes included in its boundaries vary 

 from about 200 metres to 4000 metres above sea-level. 

 The cultivated region extends up to about 1500 metres. 

 We have thus a great variety of meteorological conditions 

 brought before us in the records from the stations of the^ 

 second order which are discussed in the volume. 



Ix the .\pril number of Meicorologische Zeitschn'ft Mr. 

 E. Alt gives an interesting account of the double daily 

 oscillation of the barometer over the globe, especially with- 

 reference to the Arctic regions. He preludes his paper 

 by a resume of the efforts hitherto made to elucidate this 

 intricate problem by harmonic analysis, by Lamont, Angot, 

 Hann, and others, and gives useful explanations of the 

 several terms of the series. The theory now generally^ 

 accepted is that referred to by Lord Kelvin (Proc. Roy. 

 Soc. Edin., 1882) and developed by Prof. Margules 

 (Sitzungsher. Vienna Acad., 1890). Mr. Alt has discussed' 

 a large number of observations both on land and at sea, 

 and has exhibited the synchronous distribution of the 

 double wave of air pressure by a series of charts. With' 

 reference to the Arctic regions, observations taken mostly 

 from the Challenger report show that the maxima of the 

 oscillations occur, on an average, about iih. 20m. a.m. 

 and p.m., and of the minima, on an average, about 

 5h. 20m. a.m. and p.m. (G.M.T.). The amplitude is 

 small, amounting, on the average, to about i/io mm_ 

 The investigations of several physicists, including Prof. 

 Margules, point to the view that the synchronism of the 

 oscillation in the polar region is due to the existence of 

 a second half-daily oscillation of the atmosphere which 

 occurs in the direction of the meridians. 



We direct attention to a very laborious and important 

 work by Dr. H. Fritsche entitled " The Mean Temperature 

 of the Air at Sea-level exhibited as a Function of Longi- 

 tude, Latitude, and Period of the Year" (Meteorologische 

 Publication I.). The author has, inter alia, calculated 

 from the constants of the harmonic formula the resulting 

 values of mean temperature for the whole surface of the 

 earth, for each 10" of longitude and 5° of latitude, for 

 twenty-four equidistant epochs of the year, and for the 

 whole year, with maxima, minima, and phase times. But 

 this general description in no wise gives an idea of the 

 immense work covered by some 184 closely printed tables r 

 these are rather difficult to follow, being, with the ex- 

 planations in German, printed in facsimile lithography. 

 The calculations are based mostly on Buchan's monthly 

 and yearly isothermal charts (" Atlas of Meteorology," by- 

 Bartholomew and Herbertson). The mean yearly tempera- 

 ture of the globe is given as 14-6° C, and the amplitude 



