iv PEEFACE. 



schools, with any satisfaction to the teacher, or any profit to 

 the learner, it must be taught as systematically and as un- 

 flinchingly as Mathematics and Greek have been taught for 

 many generations. The Author is one of those who believe 

 that the time is now approaching, if it be not already here, 

 when the Natural Sciences will take their true place in school 

 education, as second to no other branch of knowledge, either 

 as regards their intrinsic value and interest, or regarded mere- 

 ly as a means of developing the mental powers. Acting upon 

 this belief, the Author has, therefore, treated his subject in a 

 purely scientific spirit ; and, while avoiding as much as pos- 

 sible the use of technicalities, he has not endeavored to lend 

 his subject any false glitter or embellishment; firmly believ- 

 ing that there is even a certain mental training involved in 

 the recognition that a strictly scientific description is not 

 without its own charms and beauties. While the use of tech- 

 nical terms has been as far as possible restricted, it is believed 

 that an explanation of every unavoidable term will be found 

 in the glossary, or is appended in the text. 



Lastly, the illustrations, with few exceptions, have been 

 drawn on the wood by the Author, and he has thought it wise 

 to wholly eschew the use of pictorial illustrations, as unneces- 

 sary in a scientific work, however elementary it may be. 



