486 



NATURE 



[September 17, 1903 



The water engrneer needs to know especially well the 

 porous and impervious rock types, the texture and composi- 

 tion of these rocks, the nature of their cements and joints, 

 and the distribution of water levels in them. Further, he 

 must know what there is to be known on the problems of 

 permeability and absorption, the relation of rain to supply, 

 the changes undergone by water and the paths taken by 

 it on its route underground, and the varying nature of rocks 

 in depth. He must also realise the effects of folds and 

 faults on drainage areas and on underground watercourses, 

 th."" special qualities of water-yielding rocks, of those form- 

 ing the foundation of reservoir sites, and those suitable for 

 the construction of dams. 



The sanitary engineer will need to be acquainted with 

 the same range of special knowledge as the water engineer, 

 but will naturally be more interested in getting rid of 

 surface water without contaminating it more than he can 

 help than in obtaining it ; he will also need a more detailed 

 acquaintance with superficial deposits than any other class 

 of professional men. 



The quarryman and architect ought to know the rocks 

 both macroscopically and microscopically, in their chemical 

 and mineralogical character, their grains and their cements. 

 But he ought to be well acquainted with the laws of bedding, 

 jointing, and cleavage, with questions of outcrop and under- 

 ground extent, and all those other characters which make 

 the difference between good and bad stone, or between one 

 desirable and undesirable in the particular circumstances 

 in which a building is to be erected. Further, he should 

 make a particular study of the action of weight and weather 

 on the rocks which he employs. 



The road engineer and surveyor, now that it has been 

 discovered that it is cheaper and better to use the best and 

 most lasting road-metal instead of any that happens to be 

 at hand, requires to have an extensive acquaintance with 

 our igneous and other durable rocks. He needs, however, 

 not only petrographic and chemical knowledge, but also a 

 type of information not at present accessible in England, the 

 relative value of these rocks in resisting the wear and 

 tear of traffic, the cementing power of the worn material, 

 and the surface characters of roads made from them, in 

 order that he may in each case select the stone which in 

 his particular circumstances gives the best value for money. 

 It would surely pay the county councils to follow, with 

 modifications, thfe example of the French and Americans, 

 and carry out a deliberate and well-planned series of ex- 

 periments on all the material accessible to them in their 

 respective districts. 



The teaching of the application of Geology should there- 

 fore take some such form as the following : — First, the 

 principles should be thoroughly taught with the use for the 

 most part of examples drawn from the economic side ; thus 

 cernenting might be illustrated on the side of water perco- 

 lation, jointing from the making of mine roads and from 

 quarry sites, faulting from effects on coal outcrops and 

 veins, unconformity from its significance to the coal-miner ; 

 while in teaching the sequence of stratified rocks the systems 

 and stages could be mainly individualised by their economic 

 characters. When this is done the class must be divided 

 into groups, each paying special attention to the points 

 which are of essential importance to them. 



The teaching at all stages should be practical and, so far 

 as can be, experimental, and in all cases where possible a 

 certain amount of field work should be attempted. For 

 the field after all is the laboratory of the geologist, where 

 he can observe experiments being made on a gigantic scale 

 under his eyes. 



The aim of the teaching should be to give to students 

 the equipment necessary to deal with the chief geological 

 problems that they will meet with in their varied pro- 

 fessions ; it should show them where to go for maps, 

 rnemoirs, or descriptions of the areas with which they are 

 dealing ; and in cases of great difficulty should enable them 

 to see where further geological assistance is required, and 

 to weigh and balance the expert evidence given them 

 against the economic and other factors of the problem 

 before them. 



From men educated thus Geology has the right to expect 

 a valuable return. There is a vast amount of knowledge 

 on economic subjects in existence but not readily accessible. 

 It has been obtained by experts, and after being used is 



NO. 1768, VOL. 68] 



locked up or lost. And yet it is the very kind of knowledge 

 which is wanted to extend our principles further into the 

 economic side of the subject. So well is this recognised 

 that many geologists are attracted to economic work mainly 

 because of the wide range of new facts that they can only 

 thus become acquainted with. It is possible to make use 

 of many of these facts for scientific induction without in 

 any way betraying confidence or revealing the source from 

 which they are obtained ; and even if they cannot be used 

 directly they are often of great service in giving moral 

 support, or the contrary, to working hypotheses founded 

 on other evidence. 



The knowledge of our mineral resources is of such vital 

 consequence to ourselves and to our present and future 

 welfare as a nation, and yet it is a matter of so much 

 popular misconception, that I feel bound to dwell on this 

 subject a little longer. To anyone who studies the growth 

 and distribution of population in any important modern 

 State the facts and reasons become as clear as day. 



It is easy to construct maps showing at a glance the 

 density of population in any country. Perhaps the most 

 effective way to do so is to draw a series of isodemic lines 

 and to gradually increase the depth of tint within them as 

 the number of people per square mile increases until abso- 

 lute blackness represents, say, more than 2000 people per 

 square mile. Such maps are the best means of displaying 

 the geography of the available sources of energy in a 

 country at any particular period, Population maps of 

 England and Wales in the early part of the eighteenth 

 century would be pale in tint with a few rather darker 

 patches, and would show a distribution dependent solely 

 upon food as a source of energy working through the 

 medium of mankind and animals. Such maps would be 

 purely agricultural and maricultural, dependent upon the 

 harvests of the land and sea. Maps made at a later period 

 would show a new concentration round other sources of 

 energy, particularly wind and water, but would not be 

 perceptibly darker in tint as a whole ; for although we are 

 apt to think that we have in this country too much wind 

 and water, they are not in such a form that we can extract 

 any appreciable supply of energy directly from them. 



r?ut maps representing the present population, while still 

 mainly energy maps, at once bring out the fact that our 

 leading source of energy is now coal and no longer food, 

 wind, or water. The new concentrations, marked now by 

 patches and bands of deepest black, have shifted away 

 from the agricultural regions and settled upon and around 

 the coalfields. The map has now become geological. 



The difference between the old and the new map is, 

 however, not only in kind ; it is even more remarkable in 

 degree. The population is everywhere mu' h denser. Not 

 only are the mining and manufacturing areas on the new 

 map more than eight times as densely populated as any 

 areas on the older map, not only is the average population 

 five times greater throughout the country, but the lightest 

 spot in the new map is nearly as dark as the darkest spot 

 on the old one. The sparsest population at the present day 

 is as thick on the ground as it was in the densest spots 

 indicated on the older map, while at the same time the 

 standards of wages, living, and comfort, instead of de- 

 creasing, have increased. 



The discovery of this new source of energy, coal, immedi- 

 ately gave employment to a much larger number of people ; 

 it paid for their food and provided the means of transport- 

 ing it from the uttermost parts of the earth. Under agri- 

 cultural conditions the map shows that the population 

 attained a given maximum density, and no further increase 

 was possible, the density being regulated by the food supply 

 raised on the surface of the land. Our dwelling-house was 

 but one story high. Under industrial conditions our 

 mineral resources can support five times the number. Our 

 dwelling-house is of five stories — one above ground and 

 four below it. 



At the same time the type of distribution is altered. The 

 agricultural areas are now covered by a relatively scanty 

 population, and the dense areas are situated on or near 

 to the coal and iron fields, the regions yielding other metals, 

 those suitable for industries which consume large supplies 

 of fuel, and a host of new distributing centres, nodal points 

 on the new lines of traffic, either inside the cou'ntry or on 



