vi THE ENGINES OF THE HUMAN BODY 



I to follow the custom of medical colleges by describing 

 the machine I had to explain in a series of fragments. I 

 therefore introduce the reader to the human body in its 

 entirety — as a complete, living, and moving machine. In 

 all of these three respects, I believe, this work differs 

 from its numerous predecessors. 



While I have made my main appeal to the general 

 reader — to the man or woman who desires to know what 

 modern medical teachers think of the marvellous con- 

 trivances of the human machine, — I hope that the account 

 here given of the human body may also appeal to medical 

 men and to professional engineers. 



I hope, too, that students of Medicine and of Biology, 

 as well as lecturers and teachers who have to impart an 

 elementary knowledge of human Physiology, may also find 

 assistance and guidance from its pages. 



I am glad to have this opportunity of thanking Sir 

 James Dewar of the Royal Institution for much helpful 

 counsel, and of acknowledging my indebtedness to Sir 

 Thomas Wrightson, Bart., M.Inst.C.E., and to Mr Allan 

 A. C. Swinton, F.R.S., M.Inst.C.E., for reading over the 

 proof-sheets of those chapters which deal with mechanical 

 and electrical contrivances. 



ARTHUR KEITH. 



October 13//7, 19 19. 



