] an'Uary 30, 1 90S] 



NA rURE 



xo\ 



The report of the Chief Inspector of Mines for the year 

 i()o4-S, issued by the Mysore Geological Department 

 (Madras, 1907), has just been received. It contains the 

 mineral statistics for 1904, and, as regards gold mining, 

 is a record of steady progress. The value of the gold pro- 

 duction in 1904 was 2,323,194/. The total value of gold 

 produced from the commencement of mining operations 

 up to the end of 1904 was 21,011,075/., and the total 

 dividends paid amounted to 9,329,487/. In addition to 

 gold, statistics are given of the production of salt, iron 

 ore, corundum, soapstone, limestone, clays, laterite, 

 granite, and other building stones. 



In a review of engineering in the United States last 

 voar, reference is made, in the Engineer of January 17, to 

 the spectacular feature of building as an engineering work 

 in the construction of the numerous steel-frame office 

 buildings of enormous height in New York. The highest 

 of these is the tower of the Manhattan Building, 75 feet 

 by 85 feet, 660 feet high to the top of the cupola. This 

 has forty-eight stories. Next to this is the tower of the 

 Singer Building, forty-two stories, with a height of 

 612 feet. The main portions of these buildings are re- 

 spectively eleven and fourteen stories high. On the other 

 hand, the City Investing Company Building has the main 

 building, twenty-five stories high, with a tower 70 feet 

 square, having thirty-two stories, and rising to a height 

 of 400 feet above the street. In all these cases the towers 

 are used as offices, &c., like the main parts of the build- 

 ing. This requires very elaborate lift equipment, with 

 high speeds. The city now has one building each of forty- 

 eight, forty-two, and thirty-two stories ; twenty buildings 

 of twenty to twenty-six stories ; fifty of fifteen to twenty 

 stories ; and 465 buildings of ten to fifteen stories in 

 height. 



W'e have received from Dr. Eredia, of the Italian Central 

 Meteorological Office, an article on the rainfall of the 

 Ligurian Riviera, reprinted from the Rivista Agraria for 

 October, 1907. This paper, like his other useful investi- 

 gations of the meteorology of various Italian provinces, 

 collects into convenient tables the most trustworthy data 

 relating to the object in view, and discusses them in an 

 interesting explanatory tSit, dealing with monthly and 

 seasonal values. The latter clearly show that in all 

 seasons of the year the rainfall along the eastern Riviera 

 is greater than along the western, and that autumn is 

 the wettest and summer the driest period. Next to the 

 autumn season, winter is wettest at Genoa, Spezzia, and 

 San Remo, i.e. near the centre and extremes of the 

 province, but at other places the greatest fall occurs in 

 the spring. The mean yearly values are 528 inches at 

 Genoa, 57-7 inches at Spezzia, and 3i'9 inches at San 

 Remo ; the period dealt with is 1880-1905. 



The Cantor lectures, delivered by Mr. Conrad Beck in 

 November and December last, have been reprinted in 

 recent numbers of the Journal of the Society of Arts 

 (December 27, 1907, to January 17); they deal with the 

 theory of the microscope, a subject of never-failing 

 interest, whether it be considered from the theoretical or 

 the practical standpoint. The first lecture deals with the 

 problem of arranging lenses so as to obtain an enlarged 

 view of an object ; although most of the matter is well 

 known, many points are considered in a most interesting 

 and instructive manner, as, for instance, the interpreta- 

 tion of the Gauss surfaces for a thick lens or system of 

 lenses. The second lecture is concerned with the quality 

 of the image formed. The methods of correcting certain 

 classes of lenses for spherical and chromatic aberration 



NO. 1996, VOL. yjl 



may be found in most books on geometrical optics, but 

 the microscope objective is so complicated in its structure, 

 and the conditions to be complied with in its design are 

 so far different from those which determine the design of 

 other lenses, that but scanty notice is generally given to 

 this most important and interesting lens combination. 

 Mr. Beck outlines the principles which must guide the 

 designer of such a lens combination. The third lecture is 

 devoted to the consideration of diffraction, so far as this 

 applies to the microscope. The theory due to the late 

 Prof. .\bbe is outlined, and Mr. J. W. Gordon's criticisms 

 of the theory are then explained ; an experiment shown 

 by Mr. Beck in his lecture proves conclusively that the 

 Abbe theory is at fault in certain respects. The fourth 

 lecture, which is concerned with the practical use of the 

 microscope, should prove of great value to those who 

 wish to eiTiploy that instrument to its greatest advantage. 



Messrs. E. B. Rosa and L. Cohen examine critically 

 the formuljE given by different authors for the self- 

 inductance of a circle in the Bulletin of the Bureau of 

 Standards for December, 1907. They consider Wien's 

 formula the most accurate. Maxwell's and Rayleigh's next, 

 Minchin's, Hicks's, and Blathy's untrustworthy, and the 

 simple formula of Kirchhoff, i.e.' L = 4?ra{log8a/r— 1.75), 

 in which a is the radius of the circle and r the radius of 

 its cross-section, as a very close approximation to the 

 correct value. 



The Journal dc Physique for December, 1907, contains 

 Prof. Schuster's address to the Soci(5t6 frani;aise de 

 Physique on. some electrical phenomena of the atmosphere 

 and their relations with solar activity. Prof. Schuster 

 points out that the most important free periods of oscilla- 

 tion of the atmosphere of the earth are, according to the 

 calculations of Lord Rayleigh and M. Margules, about 

 twelve and twenty-three hours, and that in consequence the 

 semi-diurnal motions are more pronounced than the 

 diurnal. Assuming that the conductivity of the upper 

 atmosphere is much greater than that of the lower, he 

 shows that the electric currents producecl in tne atmo- 

 sphere by its motion across the earth's magnetic field are 

 capable of explaining the diurnal variations of terrestrial 

 magnetism. The negative charges brought down by rain 

 drops he considers account for the maintenance of the 

 earth's negative charge. He points out that the evidence 

 with regard to magnetic storms and sun-spots only 

 establishes a general connection, and does not warrant us 

 in attributing a particular storm to a particular spot. 

 Finally, he urges the substitution of short organised 

 attacks on definite problems for the present rather aimless 

 accumulation of observations carried on for such long 

 periods at so many places. 



A COPY of , the prospectus of Dr. J. W. Spengel's 

 Ergebnisse und Fortschritte der Zoologie (see Nature,: 

 January 16, p. 246), giving a sketch of the lines upon 

 which that serial is to be conducted, and the names of 

 the editors for special subjects, has been received from. 

 the publisher, Mr. Gustav Fischer, Jena. 



Good pictures often serve to direct the attention of 

 children to the beauties of nature and to encourage them 

 to seek out the objects themselves in order to study them 

 at first hand. A series of beautiful slides illustrating wild 

 bird life, all of which have been made from photographs 

 taken from nature, submitted to us for inspection by 

 Messrs. Sanders and Crowhurst, should certainly succeed 

 in attracting to the observation of birds in their natural 

 surroundings those who are fortunate enough to see them. 



