1878.] 
Notices of Books. 
139 
and the method in which the young locust ruptures the shell are 
clearly described and figured. An appended map shows the 
country east of the Rocky Mountains which has been already 
overrun, and from which they will too probably spread still 
further to the eastward. The best remedy, in our opinion, 
would be the introduction of live hedges and hedgerow trees 
capable of affording abundant cover to insectivorous birds in 
place of the rail and wire fences so common in the Western 
States, and which find their thoughtless advocates in England, 
A Guide to the Determination of Rocks ; being an Introduction 
to Lithology . By Edward Jannettaz. Translated from the 
French by G. W. Plympton, C.E., A.M. New York : D. 
van Nostrand. 
This work, in its original French form, came under our notice 
some time ago (“ Quarterly Journal of Science,” v., p. 109), on 
which occasion we ventured to pronounce it a not unsuccessful 
attempt at supplying an important deficiency in geological litera- 
ture. Until the student is able to identify with moderate accu- 
racy the rocks which he meets with he has not yet learnt the 
alphabet of the science, and is unable either to make original 
observations or to verify the researches of others. Any work 
which may enable him to recognise the different rocks he sees 
when out on a geological ramble contributes something towards 
transforming him from a mere reader into a worker in the science. 
It is very true that the determination of geological species is not 
always easy, — instance the discrimination of granite and gneiss. 
Still, if the student fixes in his mind the chemical and physical 
characters of the rocks, or rather of their chief mineral constitu- 
ents as here laid down, and continually applies this knowledge in 
practice, he will find the difficulty not insurmountable. 
The first part of the book gives the properties of the principal 
minerals which compose rocks. The second is devoted to a de- 
scription of the rocks themselves ; whilst the third lays down 
systematic procedures for the practical determination of any rock 
which falls into the hands of the student. Part fourth, the 
appendix, translated from M. Stanislas Meunier’s “ Cours Ele- 
mentaire de Geologie Appliquee,” consists of a dichotomic system 
for the determination of rocks. Having no respedt for dichotomy 
as a key to classification, we must yet admit its extreme value for 
the diagnosis of species. 
it may not be out of place to notice the exceedingly elegant 
binding of this little volume. 
