358 



NA TURE 



[August 9. 1 900 



MR. BALFOUR ON SCIENTIFIC PROGRESS} 

 A PART altogether from individual likes and dislikes, is there 

 ■^ any characteristic note which distinguishes this century 

 from any that have gone before it? 



On this point I range myself with those who find the 

 characteristic note in the growth of science. In the last lOO 

 years the world has seen great wars, great national and social 

 upheavals, great religious movements, great economic changes. 

 Literature and art have had their triumphs, and have perman- 

 ently enriched the intellectual inheritance of our race. Yet, 

 large as is the space which subjects like these legitimately fill 

 n our thoughts, much as they will occupy the future historian, 

 t is not among these that I seek for the most important and the 

 most fundamental differences which separate the present from 

 preceding ages. Rather is this to be found in the cumulative 

 products of scientific research, to which no other period offers 

 a precedent or a parallel. No single discovery, it may be, can 

 be compared in its results to that of Copernicus ; no single 

 discoverer can be compared in genius to Newton ; but, in their 

 total effects, the advances made by the nineteenth century are 

 not to be matched. Not only is the surprising increase of 

 knowkdge new, but the use to which it has been put is new 

 also. The growth of industrial invention is not a fact we are 

 permitted to forget. We do, however, sometimes forget how 

 much of it is due to a close connection between theoretical 

 knowledge and its utilitarian application which, in its degree, 

 is altogether unexampled in the history of mankind. I suppose 

 that, at this moment, if we were allowed a vision of the 

 embryonic forces which are predestined most potently to affect 

 the future of mankind, we should have to look for them, not in 

 the Legislature, nor in the Press, nor on the platform, nor in 

 the schemes of practical statesmen, nor the dreams of political 

 theorists, but in the laboratories of scientific students whose 

 names are but little in the mouths of men, who cannot them- 

 selves forecast the results of their own labours, and whose 

 theories could scarce be understood by those whom they will 

 chiefly benefit. 



I do not propose to attempt any sketch of our gains from this 

 most fruitful union between science and invention. I may, 

 However, permit myself one parenthetic remark on an aspect of 

 it which is likely more and more to thrust itself unpleasantly 

 upon our attention. Marvellous as is the variety and ingenuity 

 of modern industrial methods, they almost all depend in the 

 last resort upon our supply of useful power ; and our supply of 

 useful power is principally provided for us by methods which, 

 so far as I can see, have altered not at all in principle, and 

 strangely little in detail, since the days of Watt. Coal, as we 

 all know, is the chief reservoir of energy from which the world 

 at present draws, and from which we in this country must 

 always draw ; but our main contrivance for utilising it is the 

 steam engine, and, by its essential nature, the steam engine is 

 extravagantly wasteful. So that, when we are told, as if it was 

 something to be proud of, that this is the age of steam, we may 

 admit the fact, but can hardly share the satisfaction. Our coal- 

 fields, as we know too well, are limited. We certainly cannot 

 increase them. The boldest legislator would hesitate to limit 

 their employment for purposes of domestic industry. So the 

 only possible alternative is to economise our method of con- 

 suming them. And for this there would, indeed, seem to be a 

 sufficiency of room. Let a second Watt arise. Let him bring 

 into general use some mode of extracting energy from fuel which 

 shall only waste eighty per cent, of it, and lo ! your coalfields, 

 as sources of power, are doubled at once. The hope seems a 

 modest one, but it is not yet fulfilled ; and therefore it is that 

 we must qualify the satisfaction with which at the end of the 

 century we contemplate the unbroken course of its industrial 

 triumphs. We have, in truth, been little better than brilliant 

 spendthrifts. Every new invention seems to throw a new strain 

 upon the vast, but not illimitable, resources of nature. Lord 

 Kelvin is disquieted about our supply of oxygen ; Sir William 

 Crookes about our supply of nitrates. The problem of our coal 

 supply is always with us. Sooner or later the stored-up 

 resources of the world will be exhausted. Humanity, having 

 used or squandered its capital, will thenceforward have to 

 depend upon such current income as can be derived from that 

 diurnal heat of the sun and the rotation of the earth till, in the 

 sequence of the ages, these also begin to fail. With such 



1 Address delivered by Mr. Balfour, M.P., at the opening of the 

 Cambridge Summer Meeting on August 2. Abridged from the Times. 



remote speculations we are not now concerned. It is enough 

 for us lo take note how rapidly the prodigious progress of recent 

 discovery has increased the drain upon the natural wealth of old 

 manufacturing countries, and especially of Great Britain, and, 

 at the same time, frankly to recognise _that it is only by new 

 inventions that the collateral evils of old inventions can be 

 mitigated ; that to go back is impossible ; that our only hop^ 

 lies in a further advance. 



After all, however, it is not necessarily the material and 

 obvious results of scientific discoveries which are of the deepest 

 interest. They have effected changes more subtle and perhaps 

 less obvious which are at least as worthy of our consideration 

 and are at least as unique in the history of the civilised world. 

 No century has seen so great a change in our intellectual appre- 

 hension of the world in which we live. Our whole point of 

 view has changed. The mental framework in which we arrange 

 the separate facts in the world of men and things is quite a new 

 framework. The spectacle of the universe presents itself now 

 in a wholly changed perspective. We not only see more, but 

 we see differently. The discoveries in physics and in chemistry, 

 which have borne their share in thus re-creating for us the 

 evolution of the past, are in process of giving us quite new ideas as 

 to the inner nature of that material whole of which the world's tra- 

 versing space is but an insignificant part. Differences of quality 

 once thought ultimate are constantly being resolved into differ- 

 ences of motion or configuration. What were once regarded 

 as things are now known to be movement. Phenomena appar- 

 ently so wide apart as light, radiant heat and electricity, are, 

 as it is unnecessary to remind you, now recognised as substan- 

 tially identical. From the arrangement of atoms in the mole- 

 cule, not less than their intrinsic nature, flow the characteristic 

 attributes of the compound. The atom itself has been pulverised, 

 and speculation is forced to admit as a possibility that even the 

 chemical elements themselves may be no more than varieties of 

 a single substance. Plausible attempts have been made to 

 reduce the physical universe, with its infinite variety, its glory 

 of colour and of form, its significance and its sublimity, to one 

 homogeneous medium in which there are no distinctions to be 

 discovered but distinction of movement or of stress. And 

 although no such hypothesis can, I suppose, be yet accepted, 

 the gropings of physicists after this, or some other not less 

 audacious unification, must finally, I think, be crowned with 

 success. The change of view which I have endeavoured to 

 indicate is purely scientific, but its consequences cannot be 

 confined to science. How will they manifest themselves in 

 other regions of human activity, in literature, in art, religion ? 

 The subject is one rather for the lecturer on the twentieth 

 century than for the lecturer on the nineteenth. I, at least, 

 cannot endeavour to grapple with it. 



NO 1606, VOL. 62] 



SOCIETIES AND ACADEMIES. 

 London. 



Royal Society, June 14.—" The Electrical Effects of Light 

 upon Green Leaves." By Augustus D. Waller, M.D., F.R.S. 



In the preliminary communication recently made to the 

 Royal Society, the author shows how, from the study of the 

 electrical effects of light upon the retina, he was led to ask 

 whether the chemical changes aroused by the action of light 

 upon green leaves are also accompanied by electrical effects 

 demonstrable in the same way as the eye currents. The 

 question is tested in the following way :— A young leaf freshly 

 gathered is laid upon a glass plate and connected with a 

 galvanometer by means of two unpolarisable clay electrodes 

 A and B. The half of the leaf connected with A is shaded 

 by a piece of black paper. An inverted glass jar forms 

 a moist chamber to leaf and electrodes, which are then 

 enclosed in a box provided with a shuttered aperture through 

 which light can be directed. A water trough in the 

 path of the light serves to cut out heat more or less. Under 

 favourable conditions there is obtained with such an arrange- 

 ment a true electrical response to light, consisting in the 

 establishment of a potential .difference between illuminated 

 and non-illuminated half of a leaf, amounting to 0-02 volt. 



The deflection of the galvanometer spot during illumination 

 is such as to indicate current in the leaf from excited to protected 

 part. The deflection begins and ends sharply with the begin- 

 ning and end of illumination ; it is provoked slightly by diffuse 



