September 2, 1915] 



NATURE 



15 



region, which lies between 4000 and 7000 ft. above 

 the sea. The Colorado River is the only stream that 

 maintains a strong- flow throughout the year, and 

 the meteorological records show great variations in 

 rainfall from year to year, but indicate a brief rainy 

 season in July and August. In the same number of 

 the Bulletin, Sidney Powers, of the Hawaiian Vol- 

 cano Observatory, provides some striking photo- 

 graphs of the lava-lake of Kilauea. 



The mineral and petrographic studies which form 

 a special feature of the American Journal of Science 

 air continued by W. E. Ford (vol. xl., p. 33), who 

 investigates " the relations existing between the 

 chemical, optical, and other physical properties of the 

 members of the Garnet group," and in the following 

 number by N. L. Bowen (ifetd., p. 161), who has 

 experimentally investigated the crystallisation of 

 simple types of basaltic and dioritic magmas. Mr. 

 Bowen concludes that the more acid subalkaline 

 igneous magmas are "derived from basic material, 

 being, as it were, successive mother liquors from the 

 crystallization of the basic magmas." Syenite may 

 thus arise as an upper product of differentiation from 

 a large slowly cooled mass of basaltic magma. 



The Canadian Department of Mines has issued re- 

 cently three memoirs dealing with the coal resources 

 of the Dominion ; two are issued by the Geological 

 Survey, namely, " Coal Fields of Mani,toba, Saskatch- 

 <\van, .Alberta, and Eastern British Columbia," and 

 Coal Fields of British Columbia," both by D. B. 

 Dowling, and one is issued by the Mines Branch, 

 namely, " Products and By-Products of Coal," by 

 Messrs. E. Stansfield and F. E. Carter. The two 

 first-named deal more especially with the geology of 

 the coal fields of western Canada, and will be wel- 

 comed by all interested in the geology of coal, more 

 particularly because they deal with important coal 

 deposits in relatively recent formations. Cretaceous and 

 Tertiary. The third pamphlet will no doubt appeal 

 to a wider public, its object being to present in a 

 simple and accessible form the various economic appli- 

 cations of coal products, and, in the words of the 

 authors, their "aim has been to give prominence to 

 the commercial rather than to the scientific aspect of 

 the subjects treated." Coke, gas, ammonia, tar, and 

 the derivatives of coal-tar are briefly discussed in turn, 

 and their economic and industrial importance is ex- 

 plained. Under the last head the question of the dye 

 industry is touched upon, and the authors have quoted 

 1 1 rtain statements of Dr. Bernhard C. Hesse, of New 

 rk, which well deserve the widest possible publicity, 

 iwing, as they do, a remarkably sane and^ sound 

 .ippreciation of the difficulties of the question. He 

 points out that the coal-tar dye industry is not a unit, 

 nor does it even consist of a number of independent 

 units, but " is really a conglomerate of many separate 

 parts acting and reacting upon each other, commer- 

 cially and industrially " ; his final conclusion being 

 ■ that the whole of this industry cannot be success- 

 fully ti'ansplanted, and attempts to transplant part 

 ')nly have not resulted in any self-contained and in- 

 dependent industry anywhere," 

 NO. 2392, VOL. 96] 



The Monthly Meteorological Charts of the North 

 Atlantic and Indian Oceans for September, 1915, re- 

 cently issued by the Meteorological Office, contain 

 much which is of interest to the navigator. There is 

 much else besides the precise detail as to the frequency 

 of wind and current. An inset chart is given on the 

 Atlantic issue showing the distribution of fog and mist 

 over the ocean in September. It is shown that fog is 

 seldom experienced on the steamer tracks , in mid- 

 Atlantic during September, and there is never as much 

 as 20 per cent, in that month anywhere over the North 

 Atlantic, as against 30 per cent, near Cape Race in 

 August, and 40 per cent, in July. The Atlantic chart 

 also contains on its reverse charts of the mean salinity 

 and surface temperature of the North Atlantic and of 

 the English Channel. The chart for the Indian Ocean 

 gives graphically details of the ice in the southern 

 hemisphere, also detailed information relative to the 

 results of meteorological observations in the Persian 

 Gulf and the Gulf of Oman. 



According to an article in the Scientific American 

 for August 14, Dr. F. C. Brown, of the physics de- 

 partment of the State University of Iowa, has applied 

 his discovery of the great sensitiveness to light of a 

 selenium crystal as compared with the ordinary sele- 

 nium film to the production of a " phonopticon " to 

 enable blind persons to read printed matter. The 

 instrument is a simplification and improvement of Dr. 

 Fournier's "type-reading optophone." A box carrying 

 a lamp, and provided with lenses, is moved along the 

 line of print. By this means a short vertical bar of 

 light moves along the line from left to right, and 

 an image of the bar is cast on two or more selenium 

 crystals in such a way that each crystal is covered by 

 a fixed part of the line. Each crj-stal forms one side 

 of a resistance bridge, which is balanced when the 

 bar of light falls on white paper. Want of balance 

 when the bar covers a portion of a printed letter is 

 detected by a telephone in series with a rotating con- 

 tact-maker. Each bridge has a contact-maker of a 

 difi'erent period, and on listening to the joint effect of 

 the telephones it has been found possible with not 

 more than two telephones to recognise the sequence 

 of sound for each letter of the alphabet. 



While the teaching of the calculus is now taken 

 at an early stage in our curricula, the results do not 

 appear to have been altogether satisfactory in 

 America any more than here. We have recently re- 

 ceived reprints of a discussion on "Practical Mathe- 

 matics" opened by Prof. W. S. Franklin and his 

 assistants before the Society for the Promotion of 

 Engineering Education (Bulletin iv., 10, p. 5; Pro- 

 ceedings, xxii., p. 149), and we also have before us 

 Prof. E. B. Wilson's reviews of recent text-books in 

 the Bulletin of the American Mathematical Society for 

 last June (xxi., 9). The failure of the students to 

 profit by the course would appear to be due to the 

 want of rigorous logical reasoning, to the failure to 

 illustrate the subject by concrete physical and other 

 illustrations, and to " the entire absence of sugges- 

 tiveness in his mathematical studies and the inhibi- 

 tion of sense by the excessive formalities of ordinary 



