90 



NATURE 



[September i6, 1920 



can production. The high-water marit was reached in 

 1917, when a grand total of 1-454 million tons was 

 extracted. Of this the U.S.A. produced 0-855 million 

 tons. Japan and Chile also increased their smelter 

 production to a little more than 100,000 tons. Then 

 follow Canada, Mexico, and Peru. It will be seen, 

 therefore, that by far the greater part of the world's 

 copper was derived from the western hemisphere. It 

 is evident that the U.S.A. is the largest single factor 

 in nearly every phase of the industry. At present it 

 is not only much the largest producer and consumer, 

 but it also excels in both impyorts and exports. -At 

 the beginning of 1917 the producing capacity was the 

 largest in the history of the industry, and was almost 

 ■wholly utilised. The principal producing State was 

 Arizona, followed by Montana, Michigan, and Utah. 

 These four States provided 79 per cent, of the total 

 American output in 1917. 



Mr. T. Sheppard, whose careful record of William 

 Smith's maps and memoirs has just been published 

 by Messrs. Brown and Sons of Hull, chose "The 

 Evolution of Topographical and Geological Maps " 

 as the subject of his address to the Delegates of 

 Corresponding Societies at the British Association 

 meeting in Cardiff. He showed how incomplete our 

 collections are of county maps, while such publica- 

 tions are occasionally used by dealers for the wrapping 

 of book-parcels. Great credit is very properly as- 

 signed to John Gary's work in England from 1787 to 

 1832 ; his large road-map, with the coach-roads 

 coloured in blue, is on the scale of five miles to one 

 inch, not ten as stated, and, with its index of every 

 village, is still of great value in a private library. 

 In citing maps published after the initiation of the 

 Ordnance Survey, those of Scotland by Faden and 

 Wyld, on the basis of surveys by General Roy and 

 John Ainslie (1839), and by Arrowsmith, scale four 

 miles to one inch (1840), used as the basis of Mac- 

 CuUoch's fine geological map, are worthy of men- 

 tion. MacCulloch seems to have completed his share 

 in this map in 1834. The second and most authorita- 

 tive edition of Griffith's map of Ireland was issued 

 in 1855, '^°'^ 1853, as given in the address. Attention is 

 well directed to the " soil-maps," in reality precursors 

 of our "drift-maps," published in connection with 

 agricultural and statistical surveys about the be- 

 ginning of the nineteenth century. That of London- 

 derry by Sampson in 1802, with its blue boulder-clay 

 and pink sands and gravels, interestingly anticipates 

 our modern colouring. Mr. Sheppard 's address as 

 now printed is a welcome work of reference. 



Monthly results of magrtetical, meteorological, and 

 seismological observations at the Royal Alfred 

 Observatory, Mauritius, to April, 1920, have been 

 received. Hourly observations of the magnetic 

 declination, horizontal force, and vertical force are 

 given from the photographic records. There are 

 similar observations for each hour of atmospheric 

 pressure, direction and velocity of wind, temperature 

 of the air and evaporation, amount of cloud, duration 

 of bright sunshine, and rainfall, most of which are 

 NO. 2655, VOL. 106] 



from self-registering- instruments. Monthly rainfall 

 totals are given for about loo stations in Mauritius, 

 grouped according to the river systems. The 

 monthly and yearly means and extremes of the meteoro- 

 logical elements at the Royal Alfred Observatory for 

 1919 are tabulated. July had the highest mean 

 atmospheric pressure, and February and March the 

 lowest. The absolute highest temperature was 34-9° C. 

 in January, and the lowest night minimum 13-0° C. in 

 August. The mean of the daily maxima -was highest, 

 32-1° C, in January, and lowest, 234° C, in July. The 

 mean of the night minima was lowest, 16-3° C, in 

 August, and highest, 233° C, in February. The 

 degree of humidity, saturation 100, was highest, 78, 

 in March, and lowest, 69, in November. The amount 

 of rain was greatest, 202-7 rnm., in March, and least, 

 24-3 mm., in May, the total for the year being 

 IOOI-6 mm. 



" Notes on the Ground Day Visibility at Cranwell, 

 Lincolnshire," by Capt. W. H. Pick, published by 

 the Meteorological Office as Professional Notes No. 11, 

 is an attempt to find the relations existing between 

 visibility and wind direction, wind velocity, and dis- 

 tribution of pressure. The period dealt with is from 

 February i to April 8, 1920, and for hourly observa- 

 tions from 9h. to i7h. G.M.T. It is shown that winds 

 in the south-west quadrant brought the best visibility, 

 winds between west and east through north a con- 

 siderably lower degree, and winds in the south-east 

 quadrant the lowest degree. It is pointed out that 

 visibility with winds greater than 12 m.p.h. was much 

 higher than it was with winds less than or equal to 

 12 m.p.h. Classification according to pressure distri- 

 bution shows that the mean visibility in front of a 

 depression is 5-1 of visibility-scale (0-9), in the rear 

 of a depression 5-0, and in a secondary depres- 

 sion 49. In an anticyclone or wedge it is 39 of 

 scale, in a col 4-7, and with straight isobars south to 

 north 32, west to east and south-west to north-east 

 5-5. The period of observation discussed — sixty-eight 

 days of nine consecutive hours each — is far too short. 

 The situation of Cranwell and its proximity to hills 

 would render the conditions found quite different from 

 those in many other parts of the British Isles, or 

 on the opeft sea contiguous to our coasts. The relations 

 between visibility and pressure distribution seem open 

 to doubt. No attempt has been made to ascertain 

 the relation of visibility to time of day. 



The August issue of the Journal of the Society of 

 Glass Technology contains the paper on the proper-" 

 ties of the raw fireclays found in this country which 

 was communicated to the meeting of the society in 

 April by Miss E. M. Firth, Mr. F. W. Hodkin, and 

 Dr. W. E. S. Turner. Twenty-seven clays were 

 examined, only five of them falling within the speci- 

 fication of the Refractories Research Committee of 

 the society as suitable for glass-furnaces. The results 

 show no correlation between the physical properties 

 and chemical compositions of the clays, and the 

 authors conclude that the classification of clays 

 according to chemical composition is premature, and 



