Reviews— J. J. Harris Teall’s Petrography. 369 
See ae Ve Ses VV SS 
I.—British PETROGRAPHY, WITH SPECIAL REFERENCE TO THE 
Ienzous Rocks. By J.J. Harris Tear, M.A., F.G.S. (London, 
Dulau & Co., 1888.) Royal octavo, pp. 470, with 47 Chromo- 
lithographic Plates. 
OR some years students have been longing for a well-illustrated 
and comprehensive work on the mineral structure of rocks. 
Memoirs on certain parts of the subject, such as Wadsworth’s 
Lithological Studies, or Zirkel’s Microscopical Petrography, were 
accessible without much difficulty ; there was the Minéralogie Micro- 
graphique of MM. Fouqueé and Lévy, with its splendid illustrations, 
but this is written too much from the mineralogical point of view 
for the ordinary student, and Professor Rosenbusch’s ‘‘ Mikroscopische 
Physiographie der massigen Gesteine,” though a treasure house of 
erudition, is vitiated by a faulty principle of classification, and is 
almost without illustrations. Moreover, it is not every student who 
can read French or German with as much facility as English. 
We have now a book in our own language which is comparable in 
its illustrations with that of Fouqué and Lévy, and in its erudition 
with the treatise of Rosenbusch. True, it deals only with British 
rocks, but these are so comprehensive, that there is comparatively 
little wanting to make it a complete work of reference so far as those 
of igneous origin are concerned. 
The work is illustrated by several woodcuts interspersed in the 
text and by 47 coloured plates—the former occasionally leave some- 
thing to be desired in clearness, but the latter as a rule are excellent, 
and are accompanied by outline key-plates. The examples on 
the whole appear to be very judiciously selected. The task before 
Mr. Teall was not quite so difficult as the proverbial decanting the 
Ocean into a pint pot; but still the plethora of wealth must have 
caused him no little embarrassment. If we were disposed to take 
exceptions, we should say that a little too much favour had been 
shown to the more basic rocks, though in these we still desiderate a 
tachylite, and to the pyroxenic group of minerals, and that the 
selection of the non-igneous rocks, necessarily a very restricted one, 
was not in every case the best possible. Of the 47 plates, rather 
more than eight are devoted to the peridotites, picrites, and serpen- 
tines, and it takes full thirty plates to get clear of the more basic 
half of the igneous rocks. Thus, the more acid group—granites, 
quartziferous felstones, pitchstones, and kindred rocks—seem to us 
rather inadequately represented. It is, no doubt, difficult among so 
many excellent figures to suggest excision, but we doubt whether 
two are needed in the case of quartzite, and whether the student will 
learn much from that of a crushed quartzite. Indeed, either the 
figure is not very successful, or the rock prior to its deformation was 
not very like the normal quartzite represented in the upper part of 
the plate, but must have been a much “dirtier” example. Again, 
the deformed volcanic breccia in plate xlv. should have been placed 
side by side with a normal specimen. Indeed, throughout the book 
