April 20, 1905] 



NA TURE 



591 



Messrs. W. Stanford and Co., of Oxford, have sent 

 us specimens of a number of outline maps of the world, on 

 Mollweide's equal-area projection ; also a map of the 

 Atlantic Ocean, on the same projection. The maps are 

 well drawn and clearly printed ; the larger scale maps 

 should be extremely useful for purposes of research and 

 teaching, while the smaller maps are well adapted for 

 museum use. The employment of equal-area maps in re- 

 presenting distribution cannot be too strongly recom- 

 mended, and in providing such maps at very moderate 

 prices Messrs. .Stanford have done good service. 



In ore-dressing operations and in laboratory work much 

 confusion is caused by the practice of describing the sieve 

 or screen employed by the number of the mesh. A sieve 

 of 30 mesh, for example, does not possess an aperture of 

 one-thirtieth of an inch, nor does it yield a product of 

 which the largest particles will be one-thirtieth of an 

 Inch in diameter. With coarse sieves the error is not of 

 great moment, but with fine sieves the wire itself occupies 

 so much space that the size of the particle passed by the 

 sieve may vary from a quarter to two-thirds of the size in- 

 dicated by the word "mesh." Consequently, in ordering 

 wire screens or in recording results it is desirable to 

 specify the size of aperture rather than the number of the 

 mesh. In order to enable this to be done, Mr. G. T. 

 Holloway has drawn up a valuable series of tables, calcu- 

 lated on the British Imperial Standard wire gauge, 

 showing the size of aperture, in screen wire cloth of all 

 the principal sizes in use down to the very finest. The 

 tables have been duplicated, one series showing the figures 

 in decimals of an inch, and the other, for the use of 

 those who still prefer to employ vulgar fractions, in both 

 decimals and vulgar fractions. The tables, which have 

 been published in pamphlet form {BuUclin No. 5 of the 

 Institution of Mining and Metallurgy), have been calcu- 

 lated with great care, and should do much towards effect- 

 ing uniformity in the nomenclature of sieve-mesh. 



The Geological Survey of Western Australia is publish- 

 ing, in handy octavo form, a valuable series of bulletins, 

 of which we have received three. One of them, dealing 

 with the mineral production of the colony up to the end 

 of iq03, is written by Mr. A. Gibb Maitland and Mr. 

 C. F. y. Jackson. It shows that the total value of the 

 mineral products was 47,779,000!., gold alone representing 

 a value of 46,441,000/. Other minerals mined include 

 copper, tin, lead, silver, iron, antimony and cobalt ores, 

 coal, graphite, limestone, precious stone, mica, asbestos, 

 and salt. In the other bulletins Mr. C. G. Gibson deals 

 with the mineral resources of the Murchison goldfield and 

 of Southern Cross, Yilgarn goldfield. The reports and 

 the accompanying coloured maps throw much light on 

 the geology of the districts, and indicate that the areas 

 described deserve more attention from the mining pro- 

 spector than they have hitherto received. The Murchison 

 goldfield is of some historical interest in that in 1S55, when 

 its economic value was purely prospective, it was officially 

 stated to have the appearance of being one of the finest 

 goldfields in the world. Although it has not come up to 

 these high expectations, it is one of the most important 

 goldfields in the colony, and contains not only one of the 

 largest quartz veins mined anywhere, hut also the iron 

 ore deposits of the Weld range, which, though practically 

 valueless owing to their inaccessibility, arc among the 

 richest in the world. 



Mr. \'. Kousnetzoff communicated to the Bulletin of 

 the St. Petersburg Academy of Sciences of September last 

 some useful formula for the determination of the height 



NO. 185 I, vol.. 71] 



of aurora borealis. He also gave tabular and graphical 

 results of its occurrence at Pavlovsk from January i, 

 187S, to the end of 1903. The tables show, generally, an 

 eleven years' period, as in the case of sun-spots, but the 

 details of the two curves do not correspond. The maxima 

 of the aurorse occurred in 1887 and 1896, and the minima 

 in 1884 and 1894, but this divergence may be due to the 

 occurrence of cloud. The annual period is well marked, 

 the maxima being in March and October, and the minima 

 in January and July. 



In the Archives des Sciences physiques et naturelles of 

 March last M. F. A. Forel summarises his own observ- 

 ations and those made by others on the occurrence of 

 Bishop's Ring, following the great volcanic eruption of 

 Mont PeMe (Martinique) on May 8, 1902. Bishop's Ring, 

 as most of our readers are aware, consists of a solar 

 corona of great diameter ; it appears to be formed of two 

 parts, a limb of a dazzling silvery hue being immediately 

 round the sun, and, beyond this, a coppery red ring 

 of some 20°-25° exterior radius. The ring appears to have 

 been first observed in the winter of 1902-3, but only 

 became general towards the end of July, 1903, and was 

 constantly seen until November of that year. After that 

 time it became less frequent, and ceased altogether in 

 July, 1904. The phenomenon is best seen from an elevated 

 station, and when the sun is high above the horizon. The 

 intensity of the colours of the ring was less than in that 

 which followed the Krakatoa eruption in 18S3. 



Bulletin No. 35 of the United States Department of 

 Agriculture, Weather Bureau, will be found of great 

 interest to those who wish to know something about the 

 present stage of long-range weather forecasting. The first 

 chapter is written by Prof. Garriott, and presents a verifi- 

 cation of the work of the most prominent of the so- 

 called long-range weather forecasters in the United 

 States. Prof. Garriott considers chapter and verse of the 

 forecast with the actual facts, and shows conclusively 

 the fallacy of these predictions. Prof. Woodward, in the 

 second chapter, devotes his attention to the impossibility 

 of basing weather predictions on planetary influences, and 

 at the same time criticises the work of Mr. Tice em- 

 bodied in a book on the elements of meteorology. Per- 

 haps the most interesting portions of this Bulletin are the 

 pages devoted to a discussion by Prof. Garriott of the 

 subject of long-range forecasting by many of the leading 

 meteorologists of the world. It may be said to be a brief 

 review of the literature on the subject, and gives quota- 

 tions of their opinions regarding the practicability of long- 

 range work. At the end is given a summary of the re- 

 marks and opinions expressed and a series of conclusions 

 based on them, and we refer the reader to the Bulletin 

 for these conclusions. There is one which may be men- 

 tioned here, since by recent work in this country it has 

 been brought prominently forward. " Advances in the 

 period and accuracy of weather forecasts depend upon 

 a more exact study and understanding of atmospheric 

 pressure over great areas and a determination of the in- 

 fluences, probably solar, that are responsible for normal 

 and abnormal distributions of atmospheric pressure over 

 the earth's surface." 



No. 3 of vol. ii. of Le Radium contains useful articles 

 on uraniferous minerals and their deposits, and on the 

 methods used in the measurement of the quantity of heat 

 evolved by radio-active substances. 



Prof. McClelland has recently shown that the eman- 

 ation of radio-active substances does not carry an electrical 

 charge, and the same conclusion is arrived at by means 



