INTRODUCTION 9 



without their generous assistance the work would 

 probably never have been completed; the total amount 

 expended — nearly forty thousand dollars — being en- 

 tirely beyond his own resources. To Drs. F. X. Der- 

 cum, Geo. F. Barker and Horace Jayne, of the Univer- 

 sity, the Author is also indebted for much valuable 

 assistance. 



