'H. 2 1, 1876] 



NATURE 



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y Department of Zoology and Botany. 



Mr. J. Gwyn Jeffreys, F.R.S., gave an account of the biolo- 

 jal results of the voyage of the Valorous to Disco Island in 

 fJS, which will be published in full in the Proceedings of the 

 ^al Society. He urged the importance of repeated expedi- 

 ns of this kind. A century of hard work would not suffice 

 Icollect all the information that was needed. Hitherto 

 luralists had only scraped the bottom of a few acres out of the 

 111 y millions of square miles of the ocean. The British nation 

 il hitherto done very little for submarine discovery in propor- 

 m to the poorer countries of Scandinavia, which had sent out 

 pcdition after expedition, yielding the most valuable results to 

 ience. Unfortunately, the latest intelligence as to the present 

 orwegian enterprise was that their work had been much inter- 

 •ed with by tempestuous weather. An importatt result ( f Mr. 

 fi'reys' experience was the bringing up of large and small stones, 

 me very sharp, from the sea-bottom, at great depths. He 

 nught telegraphic engineers had not taken this sufficiently into 

 count in the construction of cables, having proceeded as if 

 sy had only to deal with an entirely soft bottom. The number 

 species of moUusca obtained by the Valorous was 183, of 

 lich forty were new to science. His opinion, derived from 

 rsonal knowledge of the American, as well as of the European, 

 ma, was that the submarine fauna of Davis' Straits was pre- 

 minantly European, although a number of American forms 

 re found with them. An interesting feature was the discovery 

 a number of species previously only known in a fossil state in 

 rtiary rocks far distant, as in the Mediterranean; other species 

 re remarkable because it was now for the first time shown 

 lai an enormous range in space and latitude they had, some- 

 les at least 1,200 miles. Dr. Mcintosh, of St. Andrews, 

 of. Dickie, of Aberdeen, and Dr. Carpenter gave addresses 

 pectively on the Annelids, the Diatoms, and the Arenaceous 

 )raminifera brought home by the Valorous, and confirmed 

 r. Gwyn Jeffreys in maintaining the predominance of European 

 ms. 



Mr. John Murray gave an address on oceanic deposits and 

 sir origin, based on observations on board the Challenger. He 

 scribed and exhibited specimens of various kinds of deep-sea 

 posits. He did not think the detritus of the modern land 

 s carried more than two or three hundred miles from the 

 ore. A novel constituent of the deepest sea-bottoms was 

 mice dust, which had been found in almost every region, 

 ising from submarine volcanic action. Mr. Murray thought he 

 .d never failed to find a piece of pumice, when it was carefully 

 Dked for in any of the dredgings, and he believed it to be the 

 ief origin of the deep-sea clays. Another element which 

 speared to have been detected at great depths was " cosmic 

 ijst," or dust formed from aerolites. Another interesting point 

 ,is that whenever they got into deep water, they found man- 

 .nese peroxide in nodules inclosing organic remains — sharks' 

 eth and pieces of bone. This formation seemed to be con- 

 :cted with the disintegration of volcanic rocks. Mr. Murray 

 so discussed the question whether true equivalents of the deep- 

 a deposits now made known were to be found in the series of 

 ratified rocks. If this were not the case, then it must be held 

 :at the great continents had remained substantially the same 

 |.roughout a vast length of time. 



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459 



FORCE "■ 



V T short notice it was not to be expected that I could pro- 

 duce a lecture which should commend itself to the Asso- 

 ation by its novelty or originality. But in science there are 

 ings of greater value than even these— namely definiteness and 

 curacy. In fact without them there could not be any science 

 :cept the very peculiar smattering which is usually (but I hope 

 •roneously) called " popular." It is vain to expect that more than 

 e elements of science can ever be made in the true sense of the 

 ord popular ; but it is the people's right to demand of their 

 achers that the information given them shall be at least definite 

 id accurate, so far as it goes. And as I think that a teacher of 

 ience cannot do a greater wrong to his audience than to mystify 

 r confuse them about fundamental principles, so I conceive that 

 herever there appears to to be such confusion it is the duty of 

 iscientific man to endeavour by all means in his power to re- 

 Jpve it. Recent criticisms of works in which I have had at 

 1st a share, have shown me that, even among the particularly 



Evening lecture by Prof. Tait at the Glasgow meeting of the British 

 Bociation, Sept. 8. 



well-educated class who write'forthehigherjliteraryand scientific 

 journals, there is wide-spread ignorance as to some of the most 

 important elementary principles of physics. I have therefore 

 chosen, as the subject of my lecture to-night, a very elementary 

 but much abused and misunderstood term, which meets us at 

 every turn in our study of natural philosophy. 



I may at once admit that I have nothing new to tell you, 

 nothing which (had you all been properly taught, whether by 

 books or by lectures) would not have been familiar to all of 

 you. But if one has a right to judge of the general standard of 

 popular scientific knowledge from the statements made in the 

 average newspaper — or even from those made in some of the 

 most pretentious among so-called scientific lectures— there can 

 be but few people in this country who have an accurate know- 

 ledge of the proper scientific meaning of the little word Force. 



We read constantly of the so-called " Physical Forces " — heat, 

 light, electricity, &c. — of the "Correlation of the Physical 

 Forces," of the " Persistence or Conservation of Force." To an 

 accurate man of science all this is simply error and confusion, 

 and I have full confidence that the inherent vitality of truth will 

 render the attempt to force such confusion upon the non-scientific 

 public quite as futile as the hopelessly ludicrous endeavour of the 

 Times io make us spell the word chemistry with a Y instead of 

 an E. It is true that in matters such as this last a good deal 

 depends (as Sam Weller said) "on the taste and fancy of the 

 speller " — and sometimes even absolute error is of little or no 

 consequence. But it is quite another thing when we deal with 

 the fundamental terms of a science. He who has not exactly 

 caught their meaning, is pretty certain to pass from chronic 1 

 mistakes to frequent blunders, and cannot possibly acquire a 

 definite knowledge of the subject. 



In popular language there is no particular objection to multiple 

 meanings for the same word. The context usually shows exactly 

 which of these is intended — and their existence is one of the 

 most fertile sources of really good puns, such as those of Hood, 

 Hook, or Barham. And there is no reason to object to such 

 phrases as the force *f habit, the force of example, the force of 

 circumstances, or the^^r^if of public opinion. But when we read, 

 as I did last week, in one newspaper, that the •' force " of a pro- 

 jectile from the 8r-ton gun has at last reached the extraordinary 

 amount of 1,450 ieet, in another that the " torce " of a ball from 

 the great Armstrong gun, lately made for the Italian govern- 

 ment, is expected to average somewhere about 30,000 foot-tons 

 — and in a third that the water in the boiler ot the Thunderer 

 ' ' would in a second of time generate a ' force ' sufficient to raise 

 2,000 tons one foot high " — we see that there must be, some- 

 where at least, if not everywhere, a most reckless abuse of lan- 

 guage. In fact we have come to what ought to be scientific 

 statements, and there even the slightest degree of unnecessary 

 vagueness is altogether intolerable. 



Perhaps no scientific English word has been so much abused 

 as the word "force." We hear of "Accelerating Force," 

 "Moving Force," "Centrifugal Force," "Living Force," "Pro- 

 jectile Force," "Centripetal Force," and what not Yet, as 

 William Hopkins, the greatest of Cambridge teachers, used to 

 tell us — " Force is Force " — i.e., there is but one idea denoted by 

 the word, and all force is of one kind, whether it be due to 

 gravity, magnetism, or electricity. This alone serves to give a 

 preliminary hint that (as I shall presently endeavour to make 

 clear to you) there is probably no such thing as force at all ! 

 That it is, in fact, merely a convenient expression for a certain 

 "rate." If anyone should imagine that " 3 per cent." is a sum 

 of money, he will soon be grievously undeceived. " 3 per cent." 

 means nothings more nor less than the vulgar fraction y^^. True, 

 the " 7 hree Per Cents " usually means something very substantial 

 — but there the term is not a scientific one. Think for a moment 

 how utterly any one of you, supposed altogether ignorant of 

 shipping, would be puzzled by such a newspaper heading as 

 " The White Star-Line" or " The Red Jacket- Clipper." No 

 doubt some of our scientific terms approach as near to slang as 

 do these ; but we are doing our best to get rid of them. 



A good deal of the confusion about Force is due to Leibnitz 

 and some of his associates and followers, who, whatever they 

 may have been as mathematicians, were certainly grossly ignorant 

 of some elementary parts of dynamics, insomuch that Leibnitz 

 himself is known to have considered the fundamental system of 

 the Principia to be erroneous, and to have devised another and 

 different system of his own. This fact is carefully kept back 

 now-a-days, but it is a. fact, and (as I have just said) has had a 

 great deal to do with the vagueness of the terms for Force and 

 Emrgy in some mcdern languages. In fact, in their modern 



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