446 Professor W. W. Watts— 



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 absolute blackness represents, say, over 2,U00 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. 



But 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 much denser. Not only are the mining and manu- 

 facturing 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 



