vi PREFACE. 



and equipment, under all the varying conditions to be 

 met with as to use, locality, physical conditions, etc., lias 

 too wide a range to be exhaustively treated in such a 

 brief compass as this one volume. The difficulty has been 

 to know what to include and what to omit in order to 

 keep within the prescribed limits. It is claimed, however, 

 that what has been included is the result of actual 

 practice, compiled from authentic records. 



The Author takes this opportunity of acknowledging 

 the courtesy with which many friends have replied to 

 inquiries for information. 



