"IN the following pages the attempt is made to give a reasonably full account of the achievements of the sixteenth and seventeenth centuries in the whole field of "natural" knowledge. All the sciences, including several which have not hitherto been included in histories of science, receive due attention, and details are given of all the important work done in each of them during the first two centuries of the modern period. A considerable amount of space is also allotted to the principal branches of technology. The volume, moreover, includes a fairly full account of the philosophy of the period as an aid to the understanding of the general intellectual orientation of its scientists. It is hoped that the exposition is sufficiently clear, and the illustrations sufficiently illuminating to enable the general reader to profit greatly from this history. Its primary aim, however, is to meet the needs of the serious student. For this reason the work is fully documented. The plan of incorporating a select bibliography (giving precise references) in the text will probably be found much more helpful than is the usual formal bibliography, which makes it about as easy to find the authority for a particular view as it is to find a needle in a haystack. A more formal biblio- graphy for the whole modern period will be included in the concluding volume."