vi PREFACE. 



Mr. T. P. Ceilings has devoted much care to the execution 

 of this part of the work. 



I am grateful to the publishers for the ready manner in 

 which they met my requests ; and my sincere thanks are due 

 to Mr. W. S. Fenwick, B.Sc., for his help in preparing rough 

 drawings of some of the new illustrations, in reading .proofs, 

 and for many good suggestions. He also, with Mr. A. E. 

 Ironside, has carried through the work on the Index. 



CHKISTOPHEK ADDISON. 



