Ackno wledgmen t 



The aiUhor is much indebted to 



MR. FREDERICK IV. BATCHELDER 



of the Publication Committee for 

 his very careful supervision of this 

 paper through the press and for 

 valuable suggestions in connection 

 theretvith. These services so gene- 

 rously and kindly rejidered are 

 ack?iozvledged with sincere appre- 

 ciation and gratitude . 



