1893. SOME NEW BOOKS. 225 
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 1 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 Io 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.: Mavriopteris sphenopteroides (?), Lesq. ; Neu- 
vopteris scheuchzert, Hoffm.; N. vavinervis, Bunb.; N. tenuifolia, Schl. ; 
Lepidodendyon aculeatum, Sterub.; a Cordaicarpus (2?) congruens, or Car- 
polithes covculum, Sternb. 1,900 ft.: N. scheuchzern.; N. vavinervis; N. 
tenusfolia ; Cyclopteris ; Calamophyllites goepperti, Ett.; Lepidostrobus varia- 
bilis, L. and H., and Cordatcarpus. 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. varvinervis 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- 
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 fléxus) 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 commercial speculations, hopes, and anticipations. 
Le CaoutcHouc ET LA GuTTA-PercHa. By E. Chapel. Pp. 600. Paris: 1892. 
Price 20 francs. 
Tais work, by the Secretary of the) ‘“‘@hambre 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, 7.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, 
