i86 



NATURE 



[June 21, 1900 



Some people are best traiaed in this manner, but other 

 persons with a vivid practical interest or experience in applic- 

 ation to life and work are bast trained in close touch with prac- 

 tical conditions. Medical training is the best example ; that is 

 thoroughly done. We would have other training arranged on 

 the same practical lines. The modern university will seek, so 

 far as it can, to allow for differences of aptitude, or, it may 

 be, differences of preliminary training. It will not seek to 

 force every undergraduate at first through an arts course, 

 and then through a science course, and then through a 

 technical course. It may be well to do this with professional 

 men, but not with all. Every graduate should pass through 

 these three stages before he can be turned out a useful and 

 educated citizen, fit intellectually to take his share in the work 

 of the world ; but he need not in every case of necessity take 

 them in this logical order. 



To force a boy through a course of language or history or 

 literature, at a period when for some reason he is not attracted 

 by it, is doing him but little good. It may, indeed, do him 

 harm, by breeding disgust for subjects which at a later stage he 

 might realise were necessary, and, when properly taught, en- 

 thralhng. It is love of culture, and not hatred of it, that should 

 be implanted. The so-called " preliminary in arts " course should 

 be taken compulsorily at some stage of a graduate's complete 

 career, but not necessarily at the beginning. A student who 

 has been immersed for a term in purely technical studies will, if 

 he is good for anything, turn to such humin subjects with relief; 

 and it is not fair to turn him out in the world without some 

 worthy human interest and solace. The university has failed 

 in one of its functions if it permits him to depart trained in 

 nothing but unhuman technology. 



But then, on the other hand, the arts man, the lawyer, the 

 merchant, the man of business, and still more the teacher — how 

 much better would they not be for a tinge of scientific training. 

 Their ignorance does not come home to all of them, but to 

 many it does ; and probably in middle life they strive, by attend- 

 ing popular lectures and miscellaneous semi-scientific entertain- 

 ments, to obtain a growth by a top-dressing of superficial in- 

 formation never really assimilated, seldom adequately understood. 

 A manuring of science placed low down when young would have 

 rendered the surface soil fertile, and this later growth easy, just 

 as the youthful smattering of letters renders moderately easy 

 and interesting the subsequent reading of history, or, in some 

 cases, even the learning of a new language ; but to the wholly 

 untrained person these things are, and remain, hopelessly difficult. 

 A broad training all round can only result in what specialists 

 would call a smattering— what we should prefer to call a leaven ; 

 but so long as it is not confined to a learning of trivial details, 

 but represents a grasp of some of the fundamental principles 

 of a subject, it is all that most men ever have, or can have, in 

 any branch but their own, however highly educated they may 

 be. It takes a very exceptional man to be really learned, or to 

 be able to say anything really worth hearing, off his own subject. 

 There are men who make a large portion of knowledge their 

 province, but the majority of men cannot and should not aim at 

 this. They should know one thing well, and in all else they 

 should not be entirely ignorant. 



This absence of entire ignorance is a far more valuable com- 

 modity than is usually supposed. It enables the man of affairs 

 to consult specialists with advantage. Special knowledge is 

 always available, if one knows how and where to look for it ; 

 but the man of complete ignorance is at the mercy of every 

 charlatan ; he puts his money into the wildest scheme, on the 

 one hand, and on the other he fails to realise possibilities of 

 sound application lying all about him. His enterprise and 

 power may be great, but the blight of ignorance makes him 

 useless ; and it is just this blight which is endangering our 

 continued industrial and commercial supremacy among the 

 nations of the world. 



We look to the new type of university now about to be 

 created to remedy this state of things. If Birmingham suc- 

 ceeds in its high emprise, other great cities will follow suit. 

 The experiment is one that is of interest to the whole British 

 Empire, indeed to the whole Anglo-Saxon race. 



In another article we may perhaps enter more into detail 

 concerning some of the features of the scheme ; but it is at 

 present in such extreme infancy that its features are barely 

 recognisable. It does not follow that what is immediately to the 

 front is in reality the most important or the most characteristic. 

 {To be continued.) 



NO. 1599, VOL. 62] 



THE STEADYING OF SHIPS} 

 T^HE evolution of the modern flat-bottomed merchant vessel, 

 -*• with its midship section of approximately rectangular form, 

 from its old pointed-bottomed prototype, with deep central keel, 

 has been a necessary result of commercial competition. The 

 naval architect is called on to increase the carrying capacity of 

 his vessels to the utmost extent, and a limitation is imposed on 

 their draught of water by the limited depth of harbours, docks, 

 rivers and, last but not least, ship canals. The old central keel 

 has had to disappear in order that the extra foot or two of 

 displacement might be utilised for the carriage of cargo, and a 

 substitute has had to be found for it by the attachment oj " bilge- 

 keels" or side keels projecting from the ship at the only places 

 where they could be placed without taking up valuable space- 

 namely, at the two rounded off corners of the rectangular section. 



The efficiency of bilge-keels in modifying the rolling oscilla- 

 tion of ships seems to have been for some time a debated point 

 among naval architects, and the experimental fact that the 

 extinction of oscillation produced by these keels may in some 

 instances be many times — possibly as much as ten limes — that 

 which would be inferred from determinations of the resistance 

 of a paddle oscillating in water certainly appears at a first 

 glance paradoxical. On reading Mr. Luke's paper in the Trans- 

 actions of the Scotch Shipbuilders, and subsequently Sir 

 William White's account of his experiments on the Revenge, it 

 occurred to me that the properties of discontinuous fluid motion, 

 so long a favourite study among mathematicians, might be put 

 to a useful purpose in explaining the high resistances to rolling 

 observed with the use of bilge-keels. So far from these resist- 

 ances being in contradiction with the principles of hydro- 

 dynamics, they appeared to be to a large extent in conformity 

 with our theory of free stream-lines, and this view has been 

 borne out by subsequent calculations, certainty to a far greater 

 degree than I at first anticipated. 



According to hydrodynamical theory, if a solid body is set 

 moving through or rotating in an unlimited mass of perfect fluid 

 previously at rest, the motion will continue indefinitely, pro- 

 vided that the body has no sharp edges or corners projecting 

 into the fluid, and that the velocity does not exceed certain 

 limits. The motion involves no continuous expenditure of 

 energy, and if the solid is brought to rest, the fluid will come to 

 rest, and the energy which was expended in starting the motion 

 will be recovered. If, however, the body has any sharp project- 

 ing edges, the fluid is unable to flow continuously round these, 

 and discontinuous motion is set up, a mass of dead water being 

 dragged along behind the projecting edges, and this dead water 

 being separated from the moving fluid by a " surface of dis- 

 continuity" in crossing which the velocity changes abruptly. In 

 this case the fluid motion is not destroyed when the solid is 

 brought to rest, and energy is absorbed by the fluid. The 

 theory of discontinuous motion is the basis of the well-known 

 calculations of the resistance experienced by a plane lamina 

 moving through a liquid, originally due to Kirchhoff, and subse- 

 quently developed by Lord Rayleigh, Love, Michell and others. 



The case of a ship floating in water rocking from side to side 

 differs from these ideal cases in the properties (i) that waves 

 are produced on the surface, (2) that water is not a perfect 

 fluid ; so that energy is being continuously absorbed by wave- 

 formation, and by the viscosity of the water. If the ship has 

 no sharp keels projecting into the water, these are the only 

 causes which retard the rolling of the ship, but as soon as 

 keels are attached discontinuous motions are set up, which 

 involve a further absorption of the energy of rolling, and the 

 oscillations subside much more rapidly. If we imagine the 

 ideal case of a ship floating in a perfect liquid, the surface of 

 which is coated with a perfectly rigid sheet of ice entirely 

 preventing any waves from forming, but just allowing 

 free play for the ship to roll, the oscillation would continue 

 indefinitely, provided the ship had no sharp projecting keels. 

 If, however, bilge-keels were attached, the oscillations would 

 gradually die down, the energy of rolling being absorbed by 

 the production of discontinuous motions, and being transformed 

 into kinetic energy of the liquid. 



The object of this investigation is to show that the efficiency 

 of bilge-keels in modifying the rolling of ships may be greatly 

 increased by the action of the sides of the ship itself, and is so 

 increased in a ship of section approaching to a rectangular form, 

 provided that the bilge-keels are attached at the protruding 

 1 Abstract of a paper read before the Institution of Naval Architects. 



