Jevons — Duration of S. Stafford Coal-field. 263 



Pig. 4. Portion of P. linearis, enlarged to show the cellules. 



Fig. 5. Fragment of the stipe of P. linearis, showing reproductive (?) tubercles. 



Enlarged. 

 Fig. 6. Diplograpsus Earknessii, n. sp. The straight line beside it shows the 



natural size of the specimen. 

 Fig. 7. Germ, probably of the same. Enlarged. 

 Fig. 8. Ovarian capsule, or Gonophore, unruptured, showing the strong external 



border. Enlarged. 

 Fig, 9. Another, after ruptm-e has taken place. Enlarged. 

 Figs. 10 and 11. Ovarian capsules, compressed vertically. Enlarged. 

 Figs. 12 to 15. Graptolites Sedt/ivickii{Iiastrites (rianffulatus, H.a,vkn.), with. ora.Tia.n 



capsules attached to the cellules. Enlarged. 

 Fig. 16. Another specimen, where the capsule appears to come from the common 



canal. Enlarged. 

 Figs. 17 and 18. Germs of a di-prionidian Graptolite (?). Natural size. 

 Fig. 19. Ordinary germ of the natural size, introduced for comparison. 



iTOTiciES OIF nvLsnynoiias. 



I. — On the probable Duration of the South Staffordshire Coal 



FlBLD.l 



By "W. Stanley Jevons, Esa., M.A. 



FOR some years there had been considerable anxiety concerning the 

 supposed exhaustion of the Coal-fields, but it was only since 1860 

 when Mr. Hunt published his work upon the subject that the nation 

 seemed to have been aroused to a sense of its importance. But this 

 feeling of interest might be traced back as far as 1789, when John 

 Williams seemed struck not only with the inestimable value of coal as 

 the chief motive power of the country, but he also seemed to under- 

 stand that it was necessarily of limited quantity. Previous to this time 

 it was supposed that coal was a constant growth, filling up again the 

 vacant places in the strata where it had been taken out. The fallacy 

 of this theory, however, was soon discovered ; and from that time 

 the unfortunate circumstance that coal was necessarily limited was 

 known and acknowledged. Mr. Jevons referred to the various 

 writers and speakers who had of late shown so much interest in the 

 great question as to the probable exhaustion of our coal fields, which 

 had aroused the attention of the whole nation, and had now culmi- 

 nated in the appointment of a Royal Commission to investigate it. 

 Mr. Jevons explained the method of proceeding by which this com- 

 mission are prosecuting their enquiries, referring to each of the 

 sections into which it is divided, and specifying the particular class 

 of information which each section more especially seeks to obtain. 

 On that occasion he did not intend going over the ground which had 

 been trodden by other gentlemen, who were far better acquainted 

 than he was with the resources of this particular locality. He 

 wished, however, to offer some suggestions relating to the more eco- 

 nomical use of coal in tliis country. First, he must notice the results 

 of the inquiry of Mr. Mathews, contained in a paper published in 

 the Transactions of the Society of Mechanical Engineers, which put 

 the geology and the technical data in the clearest possible light. 



1 Being the substance of a Lecture delivered by Mr. Jevons at the Midland In- 

 stitute, Birmingham, 25th March, 1867. 



