August 28, 1884] 



NA TURE 



411 



Spottiswoode and Henry Smith, dear friends of many of us, 

 and prominent members of our Association. And now, again, 

 a well-known form is missing. For many years Sir W. Siemens 

 has been a regular attendant at our meetings, and to few indeed 

 have they been more indebted for success. Whatever the occa- 

 sion, in his Presidential Address of two years ago, or in commu- 

 nications to the Physical and Mechanical Sections, he had always 

 new and interesting ideas, put forward in language which a child 

 could understand, so great a master was he of the art of lucid 

 statement in his adopted tongue. Practice with Science was his 

 motto. Deeply engaged in industry, and conversant all his life 

 with engineering operations, his opinion was never that of a 

 mere theorist. On the other hand, he abhorred rule of thumb, 

 striving always to master the scientific principles which underlie 

 rational design and invention. 



It is not necessary that I should review in detail the work of 

 Siemens. The part which he took, during recent years, in the 

 development of the dynamo machine must be known to many 

 of you. We owe to him the practical adoption of the method, 

 first suggested by Wheatstone, of throwing into a shunt the coils 

 of the field-magnets, by which a greatly improved steadiness of 

 action is obtained. The same characteristics are observable 

 throughout — a definite object in view and a well-directed perse- 

 verance in overcoming the difficulties by which the path is usually 

 obstructed. 



These are indeed the conditions of successful invention. The 

 world knows little of such things, and regards the new machine 

 or the new method as the immediate outcome of a happy idea. 

 Probably, if the truth were known, we should see that, in nine 

 cases out of ten, success depends as much upon good judgment 

 and perseverance as upon fertility of imagination. The labours 

 of our great inventors are not unappreciated, but I doubt whether 

 we adequately realise the enormous obligations under which we 

 lie. It is no exaggeration to say that the life of such a man as 

 Siemens is spent in the public service ; the advantages which he 

 reaps for himself being as nothing in comparison with those 

 which he confers upon the community at large. 



As an example of this it will be sufficient to mention one of 

 the most valuable achievements of his active life — his introduc- 

 tion, in conjunction with his brother, of the regenerative gas 

 furnace, by which an immense economy of fuel (estimated at 

 millions of tons annually) has been effected in the manufacture 

 of steel and glass. The nature of this economy is easily ex- 

 plained. Whatever may be the work to be done by the burning 

 of fuel, a certain temperature is neces-ary. For example, no 

 amount of heat in the form of boiling water would be of any avail 

 for the fusion of steel. When the products of combustion are 

 cooled down to the point in question, the heat which they still 

 contain is useless as regards the purpose in view. The import- 

 ance of this consideration depends entirely upon the working 

 temperature. If the object be the evaporation of water or the 

 warming of a house, almost all the heat may be extracted from 

 the fuel without special arrangements. But it is otherwise when 

 the temperature required is not much below that of combustion 

 itself, for then the escaping gases carry away with them the 

 larger part of the whole heat developed. It was to meet this 

 difficulty that the regenerative furnace was devised. The pro- 

 ducts of combustion, before dismissal into the chimney, are 

 caused to pass through piles of loosely stacked fire-brick, to 

 which they give up their heat. After a time the fire-brick, upon 

 which the gases first impinge, becomes nearly as hot as the fur- 

 nace itself. By suitable valves the burnt gases are then diverted 

 through another stack of brickwork, which they heat up in like 

 manner, while the heat stored up in the first stack is utilised to 

 warm the unburnt gas and air on their way to the furnace. In 

 this way almost all the heat developed at a high temperature 

 during the combustion is made available for the work in hand. 



As it is now several years since your presidential chair has 

 been occupied by a professed physicist, it may naturally be ex- 

 pected that I should attempt some record of recent progress in 

 that branch of science, if indeed such a term be applicable. For 

 it is one of the difficulties of the task that subjects as distinct as 

 mechanics, electricity, heat, optics, and acoustics, to say nothing 

 of astronomy and meteorology, are included under physics. 

 Any one of these may well occupy the life-long attention of a 

 man of science, and to be thoroughly conversant with all of 

 them is more than can be expected of any one individual, and is 

 probably incompatible with the devotion of much time and 

 energy to the actual advancement of knowledge. Not that I 



would complain of the association sanctioned by common par- 

 lance. A sound knowledge of at least the principles of general 

 physics is necessary to the cultivation of any department. The 

 predominance of the sense of sight as the medium of communi- 

 cation with the outer world, brings with it dependence upon the 

 science of optics ; and there is hardly a branch of science in 

 which the effects of temperature have not (often without much 

 success) to be reckoned with. Besides the neglected borderland 

 between two branches of knowledge is often that which best 

 repays cultivation, or, to use a metaphor of Maxwell's, the 

 greatest benefits may be derived from a cross-fertilisation of the 

 sciences. The wealth of material is an evil only from the point 

 of view of one of whom too much may be expected. Another 

 difficulty incident to the task, which must be faced, but cannot 

 be overcome, is that of estimating rightly the value, and even 

 the correctness, of recent work. It is not always that which 

 seems at first the most important that proves in the end to be 

 so. The history of science teems with examples of discoveries 

 which attracted little notice at the time, but afterwards have 

 taken root downwards and borne much fruit upwards. 



One of the most striking advances of recent years is in the 

 production and application of electricity upon a large scale — a 

 subject to which I have already had occasion to allude in con- 

 nection with the work of Sir W. Siemens. The dynamo ma- 

 chine is indeed founded upon discoveries of Faraday now more 

 than half a century old ; but it has required the protracted 

 labours of many inventors to bring it to its present high degree 

 of efficiency. Looking back at the matter, it seems strange 

 that progress should have been so slow. I do not refer to de- 

 tails of design, the elaboration of which must always, I suppose, 

 require the experience of actual work to indicate what parts are 

 structurally weaker than they should be, or are exposed to undue 

 wear and tear. But with regard to the main features of the 

 problem it would almost seem as if the difficulty lay in want of 

 faith. Long ago it was recognised that electricity derived from 

 chemical action is (on a large scale) too expensive a source of 

 mechanical power, notwithstanding the fact that (as proved by 

 Joule in 1846) the conversion of electrical into mechanical work 

 can be effected with great economy. From this it is an evident 

 consequence that electricity may advantageously be obtained 

 from mechanical power ; and one cannot help thinking that if the 

 fact had been borne steadily in mind, the development of the 

 dynamo might have been much more rapid. But discoveries and 

 inventions are apt to appear obvious when regarded from the 

 standpoint of accomplished fact ; and I draw attention to the 

 matter only to point the moral that we do well to push the 

 attack persistently when we can be sure beforehand that the 

 obstacles to be overcome are only difficulties of contrivance, and 

 that we are not vainly fighting unawares against a law of 

 Nature. 



The present development of electricity on a large scale de- 

 pends, however, almost as much upon the incandescent lamp as 

 upon the dynamo. The success of these lamps demands a very 

 perfect vacuum — not more than about one-millionth of the 

 normal quantity of air should remain — and it is interesting to 

 recall that, twenty years ago, such vacua were rare even in the 

 laboratory of the physicist. It is pretty safe to say that these 

 wonderful results would never have been accomplished had 

 practical applications alone been in view. The way was pre- 

 pared by an army of scientific men whose main object was the 

 advancement of knowledge, and who could scarcely have imagined 

 that the processes which they elaborated would soon be in use on 

 a commercial scale and intrusted to the hands of ordinary 

 workmen. 



When I speak in hopeful language of practical electricity, I 

 do not forget the disappointment within the last year or two of 

 many over-sanguine expectations. The enthusiasm of the in- 

 ventor and promoter are necessary to progress, and it seems to 

 be almost a law of nature that it should overpass the bounds 

 marked out by reason and experience. What is most to be 

 regretted is the advantage taken by speculators of the often un- 

 instructed interest felt by the public in novel schemes by which 

 its imagination is fired. But looking forward to the future of 

 electric lighting, we have good ground for encouragement. 

 Already the lighting of large passenger-ships is an assured 

 success, and one which will be highly appreciated by those tra- 

 vellers who have experienced the tedium of long winter evenings 

 unrelieved by adequate illumination. Here, no doubt, the con- 

 ditions are in many respects especially favourable. As regards 

 space, life on board ship is highly concentrated ; while unity of 



