476 



NATURE 



[September 15, 1898 



Had science, when the use of coal was introduced, been suffi- 

 •ciently advanced to devise means for smokeless combustion, an 

 •evil, which now in more senses than one darkens the lives of the 

 inhabitants of our great towns, might have been prevented from 

 attaining its present gigantic proportions. 



We are now at the beginning of another industrial epoch, 

 ■which may indeed, if power is transmitted from a distance on a 

 large scale, brighten our skies, but which threatens to saturate 

 the earth beneath us with electric currents. That these may 

 •interfere with the general comfort is evident from the injury 

 which has been done to underground pipes at Washington and 

 -elsewhere. The construction of a powerful electric railway in 

 the immediate neighbourhood of the laboratories of a college 

 "would interfere with its efficiency, and make it impossible to 

 perform experiments of certain types. In such a case, however, 

 something could be done by arranging the experiments to suit 

 the conditions under which they would have to be performed. 

 But in the case of a magnetic observatory no such protective 

 ^measures are possible. The very object of the observatory is to 

 measure the earth's field, and if that field is artificially altered, 

 no modification of the methods of measurement, however in- 

 genious, can overcome this fundamental defect. I am glad to 

 take this opportunity of acknowledging that both the danger to 

 pure science and the necessity for obviating it have been ac- 

 knowledged by those who are chiefly interested in the technical 

 applications of science ; and in particular that one of the 

 iprincipal 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 are 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 funda- 

 mental 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 the 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 Mr. 

 '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 coat- 

 ing the oceans with thin sheet iron, has not attracted the 

 attention it deserves. Whether the physical cause thus suggested 

 Sbe due to the greater depth to which the underground 

 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, respectively may be open to question, but I am 

 ipersuaded 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 progress- 

 ing, but with the mingled hopes and fears of those who still have 

 to deal with the great unsolved problem of the causes of Terres- 

 trial Magnetism and of its manifold fluctuations. This solution 

 will be most easily attained if we are not merely content to col- 

 lect 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 

 imagnetism 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. " 



NO. 1507, VOL. 58] 



SECTION C. 



Opening Address by W. H. Hudleston, M.A., F.R.S., 

 President of the Section. 



Introductory. — About this time last year British geologists 

 were scattered over no inconsiderable portion of the northern 

 hemisphere, partly in consequence of the International Geo- 

 logical Congress at St. Petersburg, and partly owing to the 

 meeting of the British Association at Toronto. From the shores 

 of the Pacific at Vancouver, on the one hand, to the highlands of 

 Armenia on the other, there were parties engaged in the invest- 

 igation of some of the grandest physical features of the earth's 

 surface. 



The geologists in Canada were especially favoured in the 

 matter of excursions. Everything on the American continent 

 is so big that a considerable amount of locomotion is required 

 to enable visitors to realise the more prominent facts. If there 

 is no great variety of formation in Canada, yet the Alpha and 

 Omega of the geological scale are there most fully represented, 

 from the great Laurentian complex at the base to the amazing 

 evidences of glacial action, in a country where it is possible to 

 travel for a whole day without once quitting a glaciated surface. 

 But Russia presented equal attractions, and in Finland almost 

 identical conditions were observed, viz. glacial deposits on 

 Archcean rocks. The great central plain of Russia, too, with 

 its ample Mesozoic deposits often abounding in fossils, offered 

 attractions which to some may have been stronger than the 

 mineral riches of the Urals, or the striking scenery of the 

 Caucasus. 



It seems almost incredible, even in this age of extraordinary 

 locomotion, that scenes so wide apart were visited by British 

 geologists last autumn. This year we are more domestic in our 

 arrangements, and Section C finds its tent pitched once more 

 on the classic banks of the Bristol Avon, and in that part of 

 England which has no small claim to be regarded as the cradle 

 of English geology. But we may go a step further. For if the 

 strata observed by William Smith during the six years' cutting 

 of the Somersetshire coal-canal imprinted their lessons on his 

 receptive mind, it is also equally true that Devonshire, Corn- 

 wall, and West Somerset first attracted the attention of the 

 •' Ordnance Geological Survey." And thus it comes to pass 

 that the region which lies between the Bristol Channel and the 

 English Channel claims the respect of geologists in all parts of 

 the world, not only as the birthplace of stratigraphical palae- 

 ontology, but also as the original home of systematic geological 

 survey. 



The city of Bristol lies on the confines of this region, where 

 it shades off north-westwards into the Palaeozoics of Wales, and 

 north-eastwards into the Mesozoics of the Midland counties. 

 There are probably few districts which display an equal amount 

 of variety within a limited circumference. The development of 

 the various formations was excellently portrayed by Dr. 

 Wright, when he occupied this chair twenty-three years ago— 

 so well, indeed, that his address might serve as text-book on 

 the geology of the district. In the following year (1876) there 

 appeared the Survey Memoir on the Geology of East Somerset 

 and the Bristol Coal-fields, by Mr. H. B. Woodward, who has 

 since contributed important memoirs on the Jurassic rocks of 

 Britain, which are so largely developed in Somerset and the 

 adjacent counties. Since that date many papers also have ap- 

 peared in various journals, and some of these, as might be ex- 

 pected, give new and perhaps more accurate interpretations of 

 phenomena previously described. In addition to this, portions 

 of the south-west of England have been geologically re-sur- 

 veyed, and in some cases new maps have been published. 



I would call especial attention to the Survey map on the 

 scale of four miles to the inch, known as the "Index-map," 

 which has recently been issued. Sheet 11 includes this par- 

 ticular district ; but if a portion of sheet 2 is tacked on 

 to its southern border, we obtain a block of country about 

 120 miles square, which has not its equal for variety of geo- 

 logical formation in any part of the world within the same 

 space. If Europe is to be regarded as presenting a geological 

 epitome of our globe, and if Great Britain is an epitome of 

 Europe, then, without doubt, this particular block of the south- 

 west, which has Bath for its more exact centre, with a radius 

 (say) of fifty miles, may be said to contain almost everything to 

 be found on the geological scale, except the very oldest and the 



