EEPORT — 1884. 



Any one of these may Avell occupy tlio life- long attention of a man of 

 science, and to bo 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 parlance. A sound knowledge of at least the principles of 

 general physics is necessary to the cultivation of any department. Tlio 

 predominance of the sense of sight as the medium of communication 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 totiferaturc 

 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 connection with the work of Sir W. 

 Siemens. The dynamo machine is indeed founded upon discoveries of 

 Faraday now more than half a century old ; but it has required the pro- 

 tracted 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 details of design, the elabo- 

 ration 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 i-egard 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 184G) 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 develop- 

 ment of the dynamo might have been much more rapid. But discoveries 

 and inventions are apt to appear obvious when regarded from the stand- 

 point 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 wc 



