404 



NA TURE 



[February 27, 1902 



turbines included) do not work so economically when running 

 much below the power for which they are designed. For the 

 long periods on which these boats are simply cruising about, the 

 coal consumed is only that of the two small triple compound 

 reciprocating engines, the steam turbines not being utilised, 

 thus reducing their "cruising " coal consumption to a minimum 

 which, when running at full speed, is only increased by the low 

 consumption derived from the use of the steam turbine. 



The marine steam turbine, forming, as it does, " one 

 of the most striking developments in the history of marine 

 engineering," is largely adopted by private enterprise ; but, as 

 Engineering points out, " it is a little surprising that at present 

 no vessel is in progress fitted with turbine machinery and built 

 for the Royal Navy." 



MECHANICAL VENTILATORS FOR MINES} 

 'T^IlIS report is the outcome of a large number of experiments 

 conducted under the directions of a strong committee of 

 eminent mining engineers. Its object was to obtain exact infor- 

 mation concerning the relative efficiencies of various ventilating 

 fans. In order to taake the comparisons of real value, the experi- 

 ments were restricted to collieries provided with two fans, each 

 of which could be used in turn ; the conditions were theiefore 

 identical in each case. Only three kinds of fans were compared, 

 viz., the Guibal, the Schiele and the Waddle, with the result 

 that the Guibal decidedly carried off the palm. But, as pointed 

 out in the report, the conclusions arrived at are not beyond 

 criticism, because the efficiencies were determined in each case 

 by taking the ratio between the so-called " useful effect in air " 

 and the indicated horse-power of the steam-engine used for 

 driving the fan, without knowing how much power was con- 

 sumed in overcoming the inherent resistance of the engine. 

 Some experiments made in Belgium in 1S99 were more satis- 

 factory, because this point was taken into consideration. Here 

 it was found that the Rateau fan had a decidedly higher 

 mechanical efficiency than the Guibal. 



The Committee has adhered to Murgue's time-honoured 

 method of comparing the resistance of any given mine to that 

 of an orifice in a thin plate. No doubt the idea of an 

 imaginary " equivalent orifice'' has served a useful purpose, but 

 a simpler and plainer way of expressing the amount of resist- 

 ance is that advocated by Hanarle ; he reckons the resistance 

 of a mine by the horse-power required to overcome it, and there 

 is much to be said in favour of his proposal to classify mines 

 according to this system. 



Long pages crowded with figures bear testimony to the pains 

 t.iken by the Committee to fulfil its task, and it is interesting 

 to find that its observations afford a verification of the two 

 fundamental formul;i: of centrifugal ventilators. Mr. Walton 

 Brown, the indefatigable secretary. of the Institution of Mining 

 Engineers, may be fairly congratulated upon the useful report 

 which he has drawn up. 



UNIVERSITY AND EDUCATIONAL 

 INTELLIGENCE. 

 Oxford. — The 233rd meeting of the Junior .Scientific Club 

 was held on February 21. Dr. Hedin, of the Jenner Institute of 

 Preventive Medicine, read a paper, chiefly an account of his 

 recent researches, on " The Proteolytic Enzymes of the Animal 

 Body." 



Mr. T. p. Kent, scholar of Christ Church, Oxford, and 

 assistant master at Cranleigh School, Surrey, h.as been appointed 

 professor of mathematics at Rondebosch College, Cape Town. 



In view of the date appointed for the coronation of their 

 Majesties, the day examinations of the Board of Education, 

 South Kensington, arranged to be held during the week ending 

 June 2S, will be held during the week ending July 5. 



An article on the use of ordnance survey maps in teaching 

 geography, contributed by Sir Archibald Geikie to the February 

 number of the Geographical Tea(hei\ directs attention to the 

 invaluable aid to the study of geography which these maps 



1 Rcpari of the Committee of tfie Norlli of Kngland Institute of Mining 

 and Mechanical Kngincers, and tlic Midland Institute of Mining, Civil and 

 Mechanical Engineers. By Mrs. M. Walton lirown. Tramnctions 0/ the 

 ImtitittioH of Mining Ensineers (vol. .wii. pp. 96-hxvii plates). 



afford. In spite of the fact that the maps are adapted to 

 instruction in the most elementary or the most advanced stages 

 of geography, and are .so cheap, they are but rarely used, and 

 the geographical lesson is usually conducted in the unintelligent 

 way with which we are all familiar. Hung upon the wall of 

 the schoolroom, the maps encourage the study of home 

 geography in the pupils, and give them facility in map-reading. 

 Attention may then be directed to the information the maps 

 contain as to the configuration or topographical features of the 

 land, the system of contouring, and the method of plotting 

 profiles or sections across a piece of ground. The teacher can 

 then pass to the intelligent consideration of the causes of the 

 varying physical features of the land, using for this purpose the 

 maps of the Geological Survey, or can derive lessons on the 

 influence of physical features upon the history and progress of 

 the inhabitants of a country. Many other similar uses can be 

 made of the maps, and by adopting Ihem geography may be 

 made a scientific study instead of a jumble of words, figures and 

 phrases. It is to be hoped that Sir Archibald Geikie's paper 

 will be read by every teacher who desires to make the geography 

 lesson a means of cultivating the intelligence. Another paper 

 in the Geographical Teacher which will assist this object is by 

 Mr. A. M. Davies, on the geography of Greater London. Mr. 

 James Bryce's address on the importance of geography in 

 education, delivered at the recent annual meeting of the Geo- 

 graphical Association and already noticed (p. 284), appears in 

 the same number of the magazine. 



A REl'ORT of the discussion on reform in the teaching of 

 mathematics, which took place at the meeting of the Mathe- 

 matical Association on January 18, is published in the Malhc- 

 malical Gazette. Prof. A. Lodge opened the discussion with a 

 paper in which he advocated the introduction of a course of 

 geometry similar to that taken in French schools. The chief 

 points in the French text-books which he desired to see intro- 

 duced are : — (l) The more orderly arrangement of propositions ; 

 {2) the entire separation of theorems from problems of construc- 

 tion, hypothetical constructions being used in proving a theorem ; 

 (3) the closer association of a proposition and its converse when 

 both are true ; (4) the adoption of arithmetical notions and 

 algebraic processes ; (5) the early introduction of simple loci ; 

 (6) insistence on accurate figures drawn by accurate and practical 

 processes; (7) practice in exercises from the very beginning. 

 In the subsequent discussion. Prof. G. M. Minchin, F.R.S., 

 gave instances of the failure of boys to understand Euclid's 

 language and methods, and also described desirable reforms in 

 the teaching and nomenclature of dynamics and hydrostatics. 

 The discussion was, however, mainly concerned with the teaching 

 of geometry, and the general opinion of the speakers was that 

 demonstrative geometry should be preceded by a course of work 

 with ruler, compasses and piotractor, in which simple measure- 

 ments and constructions formed the chief part. This has been 

 done for many years in Scottish schools and also in some 

 elementary schools in England. One speaker expressed his 

 surprise at the amount of work that could be done with a pencil, 

 ruler, a pair of scissors and a piece of paper, and others referred 

 to the value of illustrations of geometrical truths obtained with 

 similar materials. It seems, however, to have been overlooked 

 that this work has long been part of kindergarten teaching. 



SCIENTIFIC SERIAL. 



American Journal 0/ .Science, February.— On geometric 

 sequences of the coronas of cloudy condensation, and on the 

 contrast of axial and coronal colours, by C. Barus. — On a new 

 occurrence of sperrylite, by H. L. Wells and S. L. Penfield. 

 .•\ minute quantity of sperrylite, platinum arsenide, was found 

 in a specimen of platiniferous copper ore from the Rambler 

 Mine, Medicine Bow Mountains. Platinum is found in ores 

 from all parts of the mine in quantities varying from '06 to I '4 

 ounces per ton.— A cosmic cycle, by F. W. Very.— Studies of 

 Eocene mammalia in the Marsh collection, Pealiody Museum, 

 by J. L. Wortman. The present instalment deals chiefly with 

 Fatriofelis fero.x, and contains a detailed criticism of the views 

 recently expressed by 11. F. Osborn.— On a miniature anemo- 

 meter lor stationary sound waves, by B. Davis. By sufficiently 

 reducing the dimensions of the cups and vanes in the ordinary 

 anemometer, it was found possible to determine the relation 

 between the amplitude of vibration and the rate of rotation in 



NO. 1687, VOL. 65] 



