March 8. 1888] 



NATURE 



435 



"Any one of the main pleas of our argument, if 

 " established, is fatal to Darwin's theory." 



This is not, as some might hastily suppose, the sqlfr 

 la,wdation of a flippant '* paper-scientist " ; it is the de- 

 liberate statement of a clear-headed man who took 

 nothing for granted, and who never wrote on anything 

 till he felt convinced that he understood it. 



We next come to a thoroughly practical Essay on 

 Scientific and Technical Education, a subject on which 

 Jenkin was peculiarly qualified to speak. The following 

 extract may be taken as a specimen. Jenkin has been 

 alluding to the willing and valuable assistance which a 

 Teacher often receives from his higher practical students 

 in conducting some new research ; and proceeds to 

 say :— ^ 



"The rank and file— the ordinary well-meaning student 

 "who will never become a leading light in science — is 

 " worthy of our attention. If he is well educated he may 

 " become a successful manufacturer, contractor, engineer, 

 " or farmer, and sensibly increase the power an. i wealth 

 " of our country. It seems to me that this student is not 

 " so well provided for in our scientific teaching as is 

 " desirable. And the main question I propose for dis- 

 " cussion is, how we are to improve the education of this 

 " second-best young man. My own answer put briefly, 

 " is that we can teach him systematically the art of 

 " measurement. We cannot give him the hunger for 

 " knowledge, the acute logical discrimination, nor the 

 " imaginative faculty required for research ; but we can 

 "teach him how to ascertain and record facts accurately; 

 " we can bring home to him the truth that no scientific 

 " knowledge is definite except that based on the numeri- 

 " cal comparison which we call measurement ; we can 

 " teach him the best modes of making that compai-ison 

 " in respect of a vast number of magnitudes, and in teach- 

 " ing this we shall teach him to use his hands and eyes. 

 " This practical teaching gives clear conceptions to the 

 " minds of many who receive a verbal definition as a 

 " mere string of dead words. I should be glad if it were 

 "generally proclaimed that the elementary training in all 

 " our science laboratories should be a training in the art 

 "of measurement. I wish that the classes were called 

 " measurement classes. Then a student of ordinary in- 

 *.' telligence would know that by entering a given class he 

 "would learn how t-o measure those magnitudes with 

 ^' which he will have to deal in after life. The attempt to 

 '' measure them will lead him to consider their nature, 

 " and he will approach scientific study in the classroom 

 " with a faith in the reality of science which no verbal 

 "exhortation will ever give him. You may define the 

 " absolute unit of electrical resistance as accurately as 

 *' you will, and your definition shall affect the average 

 " brain to no perceptible extent ; but a young man of 

 "very ordinary education and intelligence can learn to 

 " measure resistances in ohms, and having learnt this, an 

 " ohm becomes a reality to him. Not only does the 

 ^' knowledge he has acquired make him a more valuable 

 "assistant to the engineer and contractor, but having 

 " acquired a working faith in the existence of ohms, he 

 ^'is prepared to take some trouble to understand the 

 ^'scientific definition." 



Prof. Ewing reprints in full, in the last division of the 

 work, three characteristic papers selected from Prof. 

 Jenkin's writings on Applied Science : — and he gives in 

 brief but clear abstract, and with full references, the con- 

 tents of all. This part of the work seems to be very well 

 done, and it forms a. sort of commentary on, as well as 

 ■complement of, the short article of Sir W,. Thomson's 



to which we have already alluded. These handsome 

 volumes will be specially welcomed by. practical scientific 

 men, but as we said at starting, there is much in them of 

 interest and value to all. P. G. T. 



Oil, ON TROUBLED WATERS. 

 Le Filage de VHuile. Par le Vice-Amiral G. Cloud. 

 (Paris : Gauthier-Villars, 1887.) 



THAT the great effect produced by oil in smoothing 

 troubled waters should have been so well known in 

 times past as to have passed into a proverb, and yet that 

 no general practical use of this effect should have been 

 made until the last few years, is a remarkable instance of 

 the tardiness of mankind to apply the benefits that natural 

 phenomena provide. To the Hydrographic Office of the 

 United States is mainly due the credit of bringing into 

 prominence, and forcing on the notice of seamen, in 

 various publications, the great importance of this property 

 of oil under circumstances when life and property are 

 endangered by breaking seas, and the extreme facility and 

 trifling expense of its employment. Thanks to the efforts 

 of the Americans, the facts are now well known to all 

 English-speaking mariners, and many are the instances 

 of the successful use of oil ; but, nevertheless, the 

 prejudices of many are still against it. 



The Admiralty, in 1886, issued a memorandum on the 

 subject to the fleet, largely founded on the American 

 publications. Admiral Cloud has done a like service for 

 his countrymen, and has written the best and most com- 

 plete essay on the subject, in the little brochia-c before us. 

 Drawing on the mass of experiences collected by the 

 American Office, and giving them due credit for their 

 action, he reports additional striking cases which have 

 occurred during the last year or two, and suggests many 

 practical means of employing oil under circumstances 

 other than those yet tried, or where it has to some extent 

 failed. 



The facts are briefly these. In the heaviest gales at 

 sea, when breaking seas are a source of danger to small 

 or heavily laden vessels, or an inconvenience and dis- 

 comfort to larger or more seaworthy ones, a very small 

 quantity of oil, skilfully applied to suit the circumstances, 

 spreads upon the surface of the water with marvellous 

 rapidity, and forms a perfect breakwater, the raging waves 

 being instantaneously transformed into a harmless swell, 

 which quietly lifts the shjp without any of the violent 

 shocks and blows caused by the impact of an almost wall- 

 like mass of water about to break. vSpray alone comes 

 on board in place of the sheets of water and green seas 

 which often do so much damage. Admiral Cloud calcu- 

 lates, from a number of instances where the quantity of 

 oil used and the speed of the vessel are given, that the 

 film of oil which causes this marvellous and beneficent 

 effect can be Hltle more than 1/100,000 of a millimetre in 

 thickness ! 



Experience already goes to show that a small quantity 

 of oil is more efficacious than a free appHcation of it, the 

 film apparently spreading more quickly. Less than half 

 a gallon an hour seems to secure the largest ship. fr«m 

 being boarded by the wayes. 



The ordinary method of its application is to hang small 

 canvas bags, containing about a couple of gallons of oil, so 



