adequate library, I could not have carried on the work at all 

 without his cheerful cooperation. He has examined every 

 page of the manuscript, and I owe much to his apt suggestions 

 and kindly criticism. My thanks are also due to Professor 

 Francis Ramaley for his kindness in examining the proof- 

 sheets, and to Professor J. Henderson who has perused the 

 article on the physiography. Both have given me notes of 

 much value. 



