INTRODUCTORY The human body a perfect machine—How to keep well—Outdoor sleeping—Exercise and play—Smoking—Walking Suppose you should wake up Christmas morning and find yourself to be the owner of a bicycle. It is a brand-new wheel and everything is in perfect working order. The bearings are well oiled, the nickel is bright and shiny and it is all tuned up and ready for use. If you are a careful, sensible boy you... more...