G.— ENGINEERING. 121 



that time, where I had absorbed the congenial atmosphere of a research 

 school and had hoped to spend the rest of my days in such surroundings. 

 The sudden change to a modern University like Leeds, where every 

 day and every hour of time of both students and staff were determined 

 by rigid programme, was a great shock at the time, but I now realise that 

 it was an excellent training and I shall always be grateful for the kindness 

 which I received from Professor Stroud and the wonderful example which 

 he set of conscientious devotion to duty and sacrifice of many of his 

 scientific ambitions for the good of his students. I have thus many 

 pleasant recollections of the four years I spent in these buildings and of 

 the many friendships I formed here. 



Invention as a Link in Scientific and Economic Progress. 



Invention and Discovery are so closely allied that they are often con- 

 fused. In our common speech the two terms are frequently used as 

 synonymous, and if one seeks an exact line of demarcation between them 

 one finds it difficult, if not impossible, to distinguish one from the other 

 in any but the most general terms. Both involve an increase in knowledge 

 which may be great or slight, and may have an immediate effect or may 

 take a lifetime or more to consolidate. Both involve scientific imagina- 

 tion. Each may be only a happy idea, the inspiration of a moment or 

 in some cases an accident, but the testing of the idea and its final enuncia- 

 tion as a physical truth or as a finished invention may occupy many years. 

 Newton is reputed to have discovered the theory of gravitation on seeing 

 an apple fall from a tree, but assuming that to have been the birth of the 

 idea we know that the completion of his discovery and the proof of the 

 universal law of gravitation took the best part of his lifetime and involved 

 the invention of new branches of mathematics to complete the proofs. 

 The record of Newton's work has been so ably revised during the past 

 year by Sir Oliver Lodge, Professor Turner, Sir Frank Dyson and others, 

 in connection with the Newton Bi-Centenary Celebrations, that these 

 matters must be fresh in the memory of all. 



Were I asked to distinguish between discovery and invention I would 

 say, in very general terms, that the dividing line is the same as between 

 theory and practice, between the abstract and the concrete. Discovery 

 is essentially an increase in man's knowledge of nature and its complexities, 

 and is therefore intangible. It may be a discovery of a new principle, a 

 new element, a new and hitherto unknown quality or characteristic of a 

 known substance, and so on, but the discovery, per se, has no regard to 

 any particular practical application of the new knowledge. Invention, 

 on the other hand, has its sphere in the practical application of knowledge, 

 and the knowledge used may be new or may be as old as the hills. It 

 may be, and it is often the case, that invention involves other discoveries 

 which may be complementary to the original discovery and form its 

 completion, or may be entirely unrelated to it and form the nucleus of a 

 new branch of study. It is possibly this fact, that the difficulties en- 

 countered in developing an invention often lead to new discoveries, which 

 makes it so difficult to separate discovery from invention. I think, 

 however, that this distinction in general terms is sound, that discovery 

 is mental while invention is material, and while it is true that in the large 



