PREFACE. 



The numerous illustrations, engraved by Mr. G. Thomas (65 

 South Third Street, Philadelphia), have been well executed, and 

 do credit to the artist. 



The present edition has been carefully revised, and several 

 new figures have been added; this little volume now contains 

 one hundred and sixty-four illustrations. 



W. S. W. R. 



U. S. Naval Hospital, New York. ) 

 July, 1644. ( 



