This book contains more than one thousand facts, many of which are not generally known to the average person; but all of them are of interest to humankind, and a knowledge of many of them is essential.
The author has used the simplest English, and has avoided, as far as possible, all technical or scientific terms. He has endeavored not to fall into the common error of making his explanations harder to understand than the subjects treated.
This book is not intended for the scientist, nor does it claim to be exhaustive. In the space of a few hundred pages the writer has presented the thousand or more things which are really worth knowing, and which are usually described at unprofitable length and without that simplicity of expression so essential to clearness.