i893. SOME NEW BOOKS. 231 



and it was bored in them as deep as 1,940 ft., the horizontal 

 bedding being continuous. In that thickness of 783 ft. seven seams, 

 being more than i ft. 6 ins. thick, were found. . . . Two 

 facts are to be quoted about the Dover boring — the horizontality and 

 the regularity of the beds." But this, it is pointed out, may be due to 

 the boring being just made in the axis of a fold. From analyses 

 made by M. Watteyne, he believes the coal to be of the same 

 quality as the "gras flambant" of the Belgian basin. Under similar 

 conditions of thickness and depth, the average cost of working the 

 Hainaut seams in 1890 was 10 fr. 33 c. (8s. 3d.) per ton. 



In Zeiller's report on the fossil plants (which has already appeared 

 in the Comptes Rendus of the. Academie des Sciences) the following 

 lists are given: — 1,894 ft.: Mariopteris splienopteroicics {?), 'Lesq. ; Neu- 

 ropteris scheuchzeri, Hoffm. ; N. rarinervis, Bunb. ; N. tenuifolia, Schl. ; 

 Lepidodendron acnleatum, Sternb. ; a Covdaicarpus (?) congrnens, or Car- 

 polithes corculum, Sternh. 1,900 ft.: N. scheuchzeri; N. rarinervis; N. 

 tenuifolia; Cyclopteris ; Calamophyllites goepperti, Ett. ; Lepidostrobus varia- 

 bilis, L. and H., and Covdaicarpus. 2,038 ft. : N. scheuchzeri ; Lepid. 

 lycopodioides, Sternb. ; Stigmaria ficoides, Sternb. M. Zeiller concludes 

 his report with these words : — It may therefore be concluded from , 

 the presence of these two species \N . rarinervis and N . scheuchzeri] in 

 the Dover boring, that, as presumed by Mr, Brady, the beds traversed 

 by this boring rightly belong to the upper region of the Middle Coal- I 

 measures, and, if one may state it more precisely, that they cannot 

 be either more recent than the beds of Radstock, in Somerset, or 

 more ancient than the deepest beds of the upper zone (charbons gras 

 et flextts) of the Pas de Calais. 



Analyses of the Dover Coal (lower seams) gives 83*80 carbon, 

 4-65 hydrogen, -97 nitrogen, 3-23 oxygen, with heating power in 

 units of 14,867. Eight workable seams have been met with (a total \ 

 thickness of 16 ft. 11 in.) between 1,181 and 1,875 ft- from the surface, ', 

 while the lowest yet met with, 4 ft. thick, and 2,222 ft. from the sur- \ 

 face, is, as pointed out by M. Watteyne, well within payable depth, 

 as worked in Belgium. The rest of this interesting pamphlet is taken 

 up with comm.ercial speculations, hopes, and anticipations. 



Le Caoutchouc et la Gutta-Percha. By E. Chapel. Pp. 600. Paris ; 1S92. 

 Price 20 francs. 



This work, by the Secretary of the " Chambre Syndicale des 

 Caoutchouc, Gutta-Percha, etc.," gives a complete history of the 

 origin, composition, and manufacture of the industrial products men- 

 tioned. The first 80 pages of the book deal with the history of the 

 substances, i.e., the early discoveries and uses, vulcanisation, etc. 

 The second part, pp. 81-295, treats of the botany and geographical 

 distribution of the trees producing the exudation, and appears to 

 collect together much that is valuable both from a botanical and 

 an industrial point of view. Pages 297-340, deal with the physical 

 properties, composition, action of heat and reagents, vulcanisation 

 and its alterations, and the elimination of the sulphur, while the fourth 

 part (pp. 341-519) is devoted to the manufacture and uses. The fifth 

 division of the book is reserved for Gutta-Percha, which is treated in 

 the same systematic way as Caoutchouc ; and the sixth and last part 

 deals exclusively with the commercial questions, export and import, 

 custom dues, publications especially concerned with the industry, 



