1875.] Notices of Books. 385 
text-books, and that it represents the English estimate of their 
work. The disclaimers that have been already made on the 
part of English physiologists have doubtless ere this convinced 
Dr. Hitzig and his friends that such is not the case. 
Elements of Practical Hydraulics, for the Use of Students in 
Engineering and Architecture. Third Edition. Part I. 
By Samuet Downine, LL.D. London: Longmans 
and Co. 
THE constantly extending use of water, and of machinery and 
appliances in connection therewith, renders it very desirable 
that the engineering student should be well versed in all 
branches of hydraulics, and every additional facility for acquiring 
a correct knowledge of the principles upon which that science is 
founded is well deserving of acknowledgment. ‘The present 
work—which has now reached its third edition—is one of an 
eminently high character, and having undergone a careful 
revision prior to publication, is—what such a book ought to be— 
a very complete and valuable contribution to scientific literature, 
and is no mere science text-book compiled exclusively from 
other works, and edited by one having little or no knowledge of 
the subject treated on. Mr. Samuel Downing’s name is well 
known as that of a careful author, whilst the manner in which 
the work now under review is arranged and compiled shows 
clearly that that gentleman thoroughly understands the subject 
on which he writes. This volume does little more than intro- 
duce us to the first principles of hydraulics; it consists of but 
three chapters, which treat respectively on the discharge of 
water through an orifice, and over weirs, waste-boards, or over- 
falls ; on the flow of water under variable heads, with examples 
and practical applications as applied to sluices and weirs; and 
on the flow of water through pipes, channels, and rivers. 
Under the above headings we are introduced to the first 
principles of hydraulics as applicable to irrigation, river improve- 
ment, and water supply, the whole subject being thoroughly 
worked out; and, whilst the general explanations contained in 
the text are clearly and_intelligibly given, very numerous 
formule are furnished, together with tables of co-efficients, as 
ascertained by different observers under varying circumstances. 
There are fewer works on hydraulics amongst English scientific 
literature than could be desired, but many are to be found of 
great value by French writers, and from these Mr. Downing has 
freely drawn, giving the results of experiments therein recorded, 
thus enriching the store of knowledge on this important subject 
with which his book abounds. 
