382 — oe 
The little works which are commonly published to promote the sale 
of apparatus, are rarely of much importance, beyond the primary 
objects of trade. This volume, however, of 220 pages, with the sub- 
sidiary catalogue of Mr. Davis’s friend and ingenious —— 
Mr. Joseph M. Wightman, which occupies 70 pages more, 
with the appendages about 300 pages, is a very valuable we not 
only to the experimenter, but to the philosopher. We are not aware 
that any work affords a view of the subjects which it illustrates, at once 
more condensed and complete, more luminous and exact. Some of the 
most profound theoretical deductions of this beautiful science are con- 
tained in this volume, and must greatly contribute, along with precise 
experimental directions, to the utility of the work. Here also the fine 
results of Dr. Charles G. Page (now of the Patent Office at Washing- 
ton) are presented, both in theory and practice, and will be found by 
teachers in a more tangible form than in the elaborate memoirs and de- 
scriptions of the author, as published in different volumes of this Jour- 
nal 
Having been much conversant with the instruments of Mr. Davis and 
Mr. Wightman, we can decidedly recommend them to colleges and 
academies, and to teachers generally, as being entirely worthy of their 
confidence, while they are much cheaper, not to say better, than 
hadbtamante imported from abroad. The figures given by Mr. Davis 
and Mr. Wightman, in illustration of their instruments, are beautifully 
executed, either in wood engravings, or in electrotype copies, of which 
frontispiece of Mr. Davis is an elegant example. 
5. Thoughts on a Pebble, or a First Lesson in Geology; by the au- 
thor of the Wonders of Geology. London, 1842. pp. 42.—This ele- 
gant little book, primer-like in size, and illustrated by fine colored plates 
and wood engravings, serves still to convey some of the grandest truths 
in geology. After what we know of its accomplished author, we might 
well expect, when he picks up and describes a pebble and gives us its 
history, that we should find 
—‘‘ books in the running brooks, 
Sermons in stones, and good in every thing.” 
In the features of a flint pebble—in the marine fossils which it contains, 
proving their previous distinct existence in the sea, and also its own soft 
or dissolved state—in the the imbedding of the flint in the chalk, or rather 
sition in the cavities of the cretaceous rocks from the waters of 
early ocean—in the elevation of those rocks from the deep—in the 
ion re cliffs by the waves, and in the subsequent wear- 
inding of the flinty fragments, until fins became soundest 
