383 Bibliography. 



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 collaborator, 

 Mr. Joseph M. Wightman, which occupies 70 pages more, making 

 with the appendages about 300 pages, is a very valuable present, 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 similar 

 instruments 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 

 the 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 imbedding of the flint in the chalk, or rather 

 its deposition in the cavities of the cretaceous rocks from the waters of 

 that early ocean — in the elevation of those rocks from the deep — in the 

 demolition of their sea cliffs by the waves, and in the subsequent wear- 

 ing and grinding of the flinty fragments, until they became rounded in- 



