350 



THE POPULAR SCIENCE MONTHLY.— SUPPLEMENT. 



altogether misleading. Scientific poetry, using 

 both words in their highest sense, is now impos- 

 sible. The two things are in their very nature 

 antagonistic. A scientific man may occasionally 

 be a poet also ; but he has then two distinct and 

 almost mutually incompatible natures ; and, when 

 he writes poetry, he puts science aside. But, on 

 the other hand, when he writes science, he puts 

 poetry and all its devices aside. Mark this well ! 

 A poet may, possibly with great effect on the 

 unthinking multitude, write of 



" . . . . the huger orbs which wheel 

 In circuits vast throughout the wide abyss 

 Of unimagined chaos— till they reach 

 Ethereal splendor . . . ." 



(The word " unimagined " may puzzle the 

 reader, but it probably alludes to Ovid's expres- 

 sion " sine imagine.' 1 '' For this sort of thing is 

 nothing if not classical! The contempt in which 

 " scholars" even now hold mere "physicists" is 

 proverbial. And they claim the right of using at 

 will new words of this kind, in whose company 

 even the " tremendous empyrean " would, per- 

 haps, not be quite out of place.) 



But, whether this sort of thing be poetry or 

 not, it is in no sense science. " Huge," and 

 " vast," and such like (for which, if the rhythm 

 permit, you may substitute their similars, " Ti- 

 tanic," "gigantic," etc.), good honest English 

 though they be, are utterly unscientific words. 

 In science we restrict ourselves to small and 

 rtreat, and these amply suffice for all our wants. 

 But even these terms are limited with us to a 

 mere relative sense ; and it can only be through 

 ignorance or forgetfulness of this that more so- 

 norous terms are employed. The size of every 

 finite object depends entirely upon the unit in 

 terms of which you measure it. There is nothing 

 absolutely great but the Infinite. 



A few moments' reflection will convince you 

 of the truth of what I have just said. Let us go 

 by easily comprehensible stages from one (so- 

 called) extreme to the other. Begin with the 

 smallest thing you can see, and compare it with 

 the greatest. I suppose you have all seen a good 

 barometer. The vernier attached to such an in- 

 strument is usually read to the thousandths of 

 an inch, but it sometimes leaves you in doubt 

 which of two such divisions to choose. This 

 gives the limit of vision with the unaided eye. 

 Lot us therefore begin with an object whose size 

 is about jt \t(T of an inch. Let us choose as our 

 scale of relative magnitude 1 to 250,000 or there- 

 abouts. It is nearly the proportion in which 

 each of you individually stands to the whole pop- 



ulation of Edinburgh. (I am not attempting any- 

 thing beyond the rudest illustration, because 

 that will amply suffice for my present purpose.) 

 Well, 250,000 times the diameter of our mini- 

 mum visibile gives us a length of ten feet or so — 

 three or four paces. Increased again in about 

 the same ratio, it becomes more than 400 miles, 

 somewhere about the distance from Edinburgh 

 to London. Perform the operation again, and 

 you get (approximately enough for our purpose) 

 the sun's distance from the earth. Operate once 

 more, and you have got beyond the nearest fixed 

 star. Another such operation would give a dis- 

 tance far beyond that of anything we can ever 

 hope to see. Yet you have reached it by repeat- 

 ing, at most Jive times, upon the smallest thing 

 you can see, an operation in itself not very diffi- 

 cult to imagine. Now, a8 there is absolutely 

 nothing known to science which can preclude 

 us from carrying this process further, so there 

 is absolutely no reason why we may not in thought 

 reverse it, and thus go back from the smallest visi- 

 ble thing to various successive orders of smallness. 

 And the first of these that we thus reach has 

 already been pointed to by science as at least a 

 rough approximation to that coarse-grainedness 

 which we know to exist (though we shall never 

 be able to see it) even in the most homogeneous 

 substances, such as glass and water. For several 

 trains of reasoning, entirely independent of one an- 

 other, but based upon experimental facts, enable 

 us to say with certainty that all matter becomes 

 heterogeneous (in some as yet quite unknown 

 way) when we consider portions of it whose 

 dimensions are somewhere about g^v.otg.Tnre °f 

 an inch. We have, as yet, absolutely no infor- 

 mation beyond this, save that, if there be ulti- 

 mate atoms, they are at least considerably more 

 minute still. 



Next comes the very important question — 

 How far is experimental illustration necessary and 

 useful? Here we find excessively wide diver- 

 gence, alike in theory and in practice. 



In some lecture-theatres, experiment is every- 

 thing ; in others, the exhibition of gorgeous dis- 

 plays illustrative of nothing in particular is said 

 occasionally to alternate with real or imagined 

 (but equally sensational) danger to the audience, 

 from which they are preserved (or supposed to 

 be preserved) only by the extraordinary presence 

 of mind of the presiding performers — a modern 

 resuscitation of the ancient after-dinner amuse- 

 ment of tight-rope dancing, high above the heads 

 of the banqueters, where each had thus a very 



