740 REPORT— 1898. 



technical journals, the ' Electrician,' has supported the view that industry 

 can and ought to respect the necessities of research. 



If, however, there be any who ai-e inclined to ask whether the careful 

 study of Terrestrial Magnetism has led or is leading to any definite results, 

 or whether we are not merely adding to the lumber of the world by piling 

 up observations from which no deductions are drawn, we may answer that, 

 though the fundamental secret of Terrestrial Magnetism is still undiscovered, 

 the science is progressing. In the presence of several of the most active 

 workers I will not enter into a detailed discussion of the tasks to which 

 they are devoting themselves ; I will only ask that the doubter should 

 compare a good summary of the state of the science of Terrestrial Magnetism 

 written fifteen or twenty years ago, such as that contained in the article by 

 Balfour Stewart in the ' Encyclopaedia Britannica,' with what would be 

 written on the same subject to-day. Additions would have to be made to 

 tlie descriptions of the instruments employed, to the discussion of the 

 theory of the diurnal and secular change, while such questions as the 

 reality of earth-air currents and the tracing of loci of local disturbance 

 have only been dealt with effectively in very recent times. When, too, we 

 compare the older models of the magnetic state of the earth with that 

 devised by jNIr. Henry Wilde we cannot but admit not only that a great 

 advance has been made in forming a simple diagram of the magnetic state 

 of the earth, but that it is possible that the model contains a very pregnant 

 hint as to the physical construction of the earth as a magnetic body. 



The fact that Mr. Wilde has imitated the declination and dip with 

 remarkable accuracy all over the surface of the earth by means of a simple 

 arrangement of electrical currents, and by coating the oceans with thin 

 sheet iron, has not attracted the attention it deserves. Whether the phy- 

 sical cause thus suggested be due to the greater depth to which the under- 

 ground isothermals penetrate below oceans, the bottoms of which are 

 always cold, or whether the geological nature of the rocks is different 

 below the great depressions and elevations of the earth's surface, respec- 

 tively may be open to question, but I am persuaded that the matter should 

 be more fully investigated. 



In conclusion, let me once more revert to the points on which I dwelt 

 at the beginning of this brief address. We meet with the confidence of 

 men who know that their science is progressing, but with the mingled 

 hopes and fears of those who still have to deal with the great unsolved 

 problem of the causes of Terrestrial Magnetism and of its manifold fluctua- 

 tions. This solution will be most easily attained if we are not merely 

 content to collect facts, but if we so arrange that they shall be easily 

 dealt with. To observe is our first duty, to organise our second, and if 

 these be fulfilled we may hope that a theory of terrestrial magnetism will 

 in the future crown the efforts not merely of him on whom the first 

 glimpse of the truth may flash, but of the international co-operation 

 which has, by way of preparation, made ' the crooked straight and the 

 rough places plain.' 



