viii PREFACE 



work requires care and thought on the part of the 

 teacher. 



In all the work, drawing, measuring, and weighing 

 should be insisted on wherever circumstances permit 



F. W. 



August^ 1903. 



Official duties having called me to Southern Nigeria 

 for some months, it has been impossible for me to revise 

 the final proofs. 



My deepest thanks are due to my wife for kindly 

 undertaking this laborious task, and compiling the 

 index, in addition to the valuable assistance she has 

 given throughout the progress of the work ; and in 

 particular, in preparing, especially for this book, the 

 whole of the illustrations. W. G. F. 



February 28, 1904. 



