460 



SCIENCE. 



[N. S. VOL.XVIII. No. 458. 



not at present accessible in England, the 

 relative value of these rocks in resisting the 

 vsrear and tear of traffic, the cementing 

 power of the worn material, and the sur- 

 face characters of roads made from them, 

 in order that he may in each ease 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, the 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, therefore, 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 cementing might 

 be illustrated on the side of water percola- 

 tion, jointing from the making of mine 

 roads and from quarry sites, faulting from 

 effects on coal outcrops and veins, uncon- 

 formity from its significance to the coal- 

 miner; while in teaching the sequence of 

 stratified rocks the systems and stages 

 could be mainly individualized 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 prac- 

 tical 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 experi- 

 ments 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 

 professions; it should show them where 



to go for maps, memoirs or desciuptions of 

 the areas with which they are dealing ; and 

 in cases of great difficulty should enable 

 them to see where further geological as- 

 sistance 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 ac- 

 cessible. It has been obtained by experts, 

 and after being used is 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 sub- 

 ject. So well is this recognized that many 

 geologists are attracted to economic work 

 mainly because of the wide range of new 

 facts that they can only thus become ac- 

 quainted with. It is possible to make use 

 of many of these facts for scientific induc- 

 tion without in any way betraying con- 

 fidence or revealing the source from which 

 they are obtained ; and even if they can not 

 be used directly they are often of great 

 service in giving moral support, or the con- 

 trary, to working hypotheses founded on 

 other evidence. 



The Imowledge of our mineral resources 

 is of such vital consequence to ourselves 

 an^ 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 

 any one who studies the growth and distri- 

 bution 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 gradually to increase the depth 



