The present Manual may therefore be considered only as a temporary revision and supplement of those already existing on the subject. We find now, in almost every town and village, men of education and searching enquiry among all classes of society, while individual, whatever his calling, is almost forced by circumstances to take at least a general or superficial notice of the arts and sciences which now penetrate deeper and deeper all relations of social life.For such and similar purposes has the present enlarged edition been published, to fill out to a certain extent the technical and classical chasms prevalent in the previous works.