Reports & Proceedings—Mineralogical Society. 557 
also a good deal of new matter is included. Not the least interesting 
part of the book is that dealing with the ancient river systems, 
and describing how the rivers arising in the south have had their 
valleys truncated by coast erosion, which is still going on, as may be 
seen by any visitor to Freshwater Bay and other places on the 
southern shore. It is shown, for example, how the Western Yar, 
which now opens into the Solent by a mouth disproportionately 
large for the size of the river, and rises a few yards from the sea at 
Freshwater Gate, once had a course extending eastward past Brook 
and Brighstone (here written Brixton) on the south of the chalk 
downs and as far as Blackgang and Atherfield, as is demonstrated by 
the gravels and brickearths exposed in the sections of the cliffs. 
These and other formations are well described in the chapter on 
superficial deposits. It is followed by a section on the economic 
geology, containing further new material, with good accounts 
of the different soils, of the building materials (and notably that 
supplied by the Bembridge limestone), of the road metal, the scanty 
fuel supplied by the brown coal-seams of the Bracklesham beds and 
the peat on Wroxall Down, and the phosphatie concretions and other 
minerals collected in small quantity in various parts of the island. 
The volume concludes with a chapter on the water supply. As 
already indicated the work is based on the Survey Memoir of 1889, 
but it is enriched by original observations by the author. It is 
intended to accompany the large-scale colour-printed map also issued 
by the Survey, for the map forming the frontispiece is Inadequate, 
and compares very unfavourably with that which appeared in the 
earlier Memoir. The omission of the figures of the characteristic 
fossils is to be regretted in a work intended mainly to be popular. 
The tables of fossils and the other appendices to the former Memoir 
are likewise excluded, but this may be regarded as inevitable in 
view of the small compass of the book, the present volume con- 
taining 219 pages, as against 349 pages to the Memoir of 1889. 
Nevertheless, the price of Mr. Osborne White's memoir is 10s., while 
that of the earlier and larger volume was 8s. 6d. This is a matter 
for regret, since a reliable and comprehensive book, such as 
Mr. White’s work undoubtedly is, if sold at a more moderate price 
would almost certainly command a large sale among the visitors to 
the island. 
Hee Ace Me 
REPORTS AND PROCEEDINGS. 
MINERALOGICAL SOCIETY. 
lst November, 1921.— Dr. A. Hutchinson, President, in the chair. 
Professor H. Hilton: On the determination of the optic axes of a 
crystal from extinction-angles. 
The problem of obtaining the positions of the optic axes of a crystal 
from the extinction-directions on four known faces was discussed, 
