NA TURE 



{Jjme 14, 1877 



cation and orderly arrangement of the fundamental con- 

 ceptions and laws of physical science are too often lost 

 sight of in comparison with the vast extensions which 

 these men gave to our knowledge — though their actual 

 value is probably little inferior. No doubt it is scarcely 

 possible for any one (except by accident, of which some 

 notable instances will occur to every reader) to make 

 real extensions of our knowledge unless he possesses a 

 clear conception of elementary principles. But great 

 discoverers are generally too much engrossed with their 

 higher studies to bestow much time on the explanation 

 or co-ordination of the more elementary parts of their 

 science. All the more honour, then, to those who, like 

 Gahleo and Newton, have made every step of their pro- 

 gress clearly intelligible to the student from its very 

 foundations. 



Immediately after Newton's time the progress of phy- 

 sical science was almost arrested in Britain (mainly, 

 it seems, from the want of men of a high order of 

 genius), and the really great foreign Mathematicians and 

 Physicists of the time were entirely absorbed in the rapid 

 development of their subjects. The disastrous conse- 

 quence was that the elementary parts of science were left 

 almost entirely to the second-rate men, or to the mere 

 sciolists, men whose representations of science, even at 

 the best, were mere caricatures — in the sense in which an 

 orrery mimics the solar system, or an automaton a living 

 animal; — and though, since that time, really first-rate 

 men {eg-, Cavendish and Young) have occasionally ap- 

 peared in Britain, the pernicious influence of generations 

 of smatterers was not easily shaken off. Thus an ab- 

 surdly artificial, and unnecessarily complex system, based 

 to a certain extent on Newton, but altogether devoid of 

 his wonderful precision, simplicity, and completeness, 

 came to be generally adopted here. This artificial sys- 

 tem may be said to have reached its climax in the works 

 of the late Dr. Whewell, perhaps the only brilliant writer 

 of what is known now as Paper Science, by far the most 

 pestilent weed against which the true scientific culti- 

 vator has to contend. The omniscient Master of Trinity 

 might quite probably have been able to hold his own 

 with Aristotle, had he lived in days when science had 

 but a scanty development ; but it is impossible for any 

 one nowadays to hold relatively to human knowledge 

 any such position. And he who tries to do so, even had 

 he the genius of Newton to start with, will simply do 

 nothing. 



Clerk-Maxwell (wisely, we think) appears to prefer New- 

 ton and Rowan Hamilton to Whewell, on whom or the like 

 of whom his rivals mainly rely. And this alone accounts 

 for a great deal of the extraordinary dissimilarity between 

 the works to which we have alluded. What is Whewell, the 

 universal genius, with all his book-learning, in comparison 

 with Newton, the special genius, with his close and patient 

 study of material phenomena themselves ? Nothing. Men 

 consulted Whewell as they would a dictionary or an ency- 

 clopaedia, simply to save themselves trouble. But when 

 was an encyclopajdia ever seen to add a volume of new 

 matter to itself as an appendix ? To use an old com- 

 parison, Newton, as it were, studied Chinese metaphysics 

 in China itself, at head-quarters ; Whewell and those who 

 do like him read all the European works on China and all 

 the European works on metaphysics, and " combine their , 



information." Thus almost all Clerk-Maxwell's rivals 

 — whom therefore we need not specially name — give us 

 the sacred Three Classes of Levers, the various Systems 

 of Pulleys, the altogether imaginary gold shell of the 

 Florentine Academicians, the Principle of Repulsion, the 

 Transmissibiliiy of Fluid Pressure, and what not. Weight 

 and specific gravity are usually put forward in preference 

 to mass and density — the accidental property before the 

 inherent or essential one ! We have the old confusing 

 statements about a co-efficient of elasticity in the impact 

 of balls. In one of the most pretentious of these 

 works we are told that the " strict " definition of a level 

 surface implies that " at all points of it the force of gravity 

 has the same value, and its direction is at right angles to 

 the surface." That is to say, the author here uses the 

 word '-force" in two difterent senses. It means the 

 " potential energy of a given mass," when its value is 

 spoken of ; but it means the " weight of a given mass '' 

 when its direction is spoken of. For it is inconceivable 

 that the author could have meant to state that the 

 weight of a body is the same at all points of a level surface. 

 Wc could give without practically any limit instances of a 

 similar kind (not mere slips of the pen, trom which no man's 

 work can be free), but we will be merciful, and simply ex- 

 tract the following passages, putting a word or two in 

 italics, and leaving the reader to exercise himself in finding 

 what is erroneous : — 



" An arrow shot upwards from a bow reaches to a cer- 

 tain height : show that if the weight of the arrow be 

 doubled, other circumstances remaining the same, the 

 height reached will be one-fourth of its former value." 



" Gravity and distance together represent theyivtY- em- 

 ployed from the beginning in putting things where they 

 are, and whenever they come together by attraction they 

 develop a corresponding force or heat." 



" When heat is continually applied to water it is found 

 that if the water is in an open vessel its heat cafinot be 

 raised beyond a certain point." 



" The forces of heat, electricity, magnetism and light 

 are now considered to be all species of motion, discover- 

 able and measurable only by the amount of movement 

 they can produce or counteract." 



"... water is boiled by placing a lamp beneath the 

 flask so that the upper part of the flask becomes full of 

 steam, the air being expelled. The flask is now stopped 

 with a cork, removed from the lamp, and allowed to 

 cool. ... By pouring cold water . . the water begins 

 to boil again. The experiment requires great care to 

 prevent accidents." 



" Matter in motion is FORCE." 



" Electrical attraction is the name given to some cases 

 resembling magnetic attraction, in which electricity is the 

 agent." 



'■■ Liquids possess a small hut very perfect elasticity, 

 which differs in amount in different liquids." 



"... gold, which in the case of a sovereign falls as 

 fast as anything which we have commonly in view, may 

 be beaten out to a thin leaf which almost floats ok 

 the air . . ." 



" // is sometimes stated incautiously, that the weight of a 

 body may always be supposed to be collected at the centre 

 of gravity, but the present case shows that such a state- 

 ment is too loide." 



There is nojustifying the existence of anew way of doing 

 anything except by showing that it is better than the old 

 one ; but, if that can be done, the new way is justified. 

 And, as it is not our interest to become Encyclopsdias, 

 when we get a good new way, let us adopt it, and at once 



