PREFACE. 



ON*E of the most interesting features of our time, is the great advance which has been 

 made in the study of the various branches of Science. But a few years only has 

 elapsed, since philosophy was confined to those who had received a collegiate 

 education, or were engaged in the learned professions. By slow degrees, our public 

 schools adopted the pure mathematics as a portion of their curriculum ; whilst the 

 schools, in which the masses were educated, ignored entirely the study in every form. 

 It was even considered that a knowledge of Science, by calling too strongly on the 

 mental powers, would unfit the youth for commercial pursuits; and the expensive 

 character of such studies, on the other hand, limited them to those whom ample 

 means placed beyond such considerations. 



The nation owes a deep debt of gratitude to those noble pioneers of intellectual 

 advancement, Lord BROUGHAM and Dr. BIRKBECK, who were among the first to break 

 down the barriers which stood between the " people" and the " learned." The 

 former, by his untiring exertions in connection with the Society for the Diffusion of 

 Useful Knowledge, and the latter by the establishment of Mechanics' Institutes, 

 have done immense good to the masses, and have earned the deepest gratitude of 

 their countrymen. It was prophesied against the issue of their labours, that the 

 masses would soon over-ride their employers, and that sedition and infidelity would 

 become rampant in the land. How far such prophecies have been falsified has been 

 shown by recent events, in which we have seen hundreds of thousands of our artisans 

 suddenly plunged from prosperity to want, by circumstances beyond their control, 

 and bearing their afflictions with an intelligent resignation unequalled in the 

 history of mankind. There is no impropriety in alleging the cause of this noble 

 feeling to be due, in a great measure, to the advancement of knowledge, and to the 

 mental culture which such individuals have acquired by the means to which we have 

 briefly alluded. 



The present state of Education, the exigencies of Agriculture and Manufactures, 

 together with a high appreciation of the pleasures and advantages of Science, have 

 created a great demand for works devoted to the subject. At first sight, it would seem 

 that abundant means had been afforded to supply this demand; but a little considera- 

 tion will suffice to show that this idea is erroneous. Even with all the advantages of 

 cheap literature, there scarcely yet exists a systematic arrangement by which 

 ns, unaided by scholastic- training, may hope to arrive at a competent knowledge 

 of the numerous branches into which the study of nature is now divided. For want 

 of personal experience, such cannot properly select for themselves those works most 

 fitted to instruct them ; and, in the attempt so to do, they often experience great 

 disappointment, partly from technicalities, unfortunately too prevalent in our scientific 

 expositions; and frequently, from the abstruse or obscure style in which those works 

 are veiled. The practical man, again, has often to supply himself with many works 

 on the same subject, in order to acquire both the theory and applications of it; 

 hence much labour, patience, and expense are necessarily incurred, which too often 

 eti'I in weariness and disgust. 



