190 
POPULAR SCIENCE REVIEW. 
kept absolutely to an alphabetical order, certainly the most convenient for 
reference ; at the same time certain articles have been collected under special 
heads, but always, where necessary, with cross-references. By the use of 
black letter for the names of authors, &c., the book is rendered particularly 
easy to consult. 
GEOLOGICAL SURVEY OF ESSEX AND HERTS.* 
W E have received from the authors a copy of the memoir on Sheet 47 of 
the Geological Map of England and Wales, published under the 
superintendence of Mr. Whitaker, in which that gentleman and his colleagues 
carry farther to the northward the geological survey of the London basin, 
so well treated by him in a former memoir. The present work relates to the 
north-west of Essex and north-east of Hertfordshire^ and takes in small 
portions of Cambridgeshire and Suffolk. It thus carries the survey of the 
London basin up to its northern boundary, where Cretaceous beds occur ; and 
the greater part of the remainder of the area is formed by the London Clay, 
the exposure of the Thanet and Reading beds being very small. The surface 
is covered to a great extent with drift deposits of various kinds ; but traces 
of the Red Crag are met with here and there in the north-eastern part of the 
area, especially in the neighbourhood of Sudbury. The memoir displays the 
usual accuracy and completeness characteristic of all work with which Mr. 
Whitaker has anything to do ; but, good as it is, we do not understand why its 
cost should be quite so high — three-and-sixpence for a pamphlet of ninety- 
two pages, with nineteen woodcuts, will seem to unsophisticated people a 
little too much 
WILLIAM HARVEY.f 
H OW easy it is to depreciate ; how hard it was to demonstrate the circu- 
lation of the blood ; how incomprehensible it is to the multitude that 
scientific men should be so long in finding out such very evident things, 
are expressions which always must come forth on reading any life of William 
Harvey, and the criticisms of his contemporaries and successors. Poets, 
play-writers, and imaginative but not practical anatomists, had stated that the 
blood moved here and there, and that there was a circulation of it ; but 
Harvey demonstrated the true circulation of the blood, and did not deal 
with fantastic imagery or a cyclical movment which, like that of Osesalpinus, 
was not the true one. Why was the great fact that the arterial blood 
is propelled forth by the heart, and that it enters the veins by minute capil- 
laries and returns, not found out before so late in the world’s history ? Its 
elaboration was opposed by the prejudices of mankind, by the pernicious 
* “ Memoirs of the Geological Survey, England and Wales. The Geo- 
logy of the North-West Part of Essex and the North-East Part of Herts 
(explanation of Sheet 47 of the Map).” By W. Whitaker, W. H. Penning, 
W. H. Dalton, and F. J. Barnett. 8vo. London : Printed for Her Majesty’s 
Stationery Office. 1878. 
t “ William Ilarvey. A History of the Discovery of the Circulation of 
the Blood.” By R. Willis, M.D. London : C. Kegan Paul & Co. 1878. 
