PREFACE. ' XV 



to Mr. Dunkin, for tlie great labour and care lie 

 has shown in personally computing my observations, 

 and to Mr. J. R. Hind, the distinguished astronomer, 

 for many acts of kindness. To Mr. Glaisher I am 

 indebted for the benefit of his great experience 

 in the testing of my aneroids. It was my good 

 fortune, when preparing for my last expedition, to 

 receive tokens of good-will from many persons, some 

 of whom were personally unknown to me. I have 

 mentioned in the body of the work the names of 

 some of these friends ; and I must not omit to add to 

 the list those of Messrs. Howard and Co., who pre- 

 sented me with an ample stock of quinine, which 

 proved of great service to me. 



Lastly, I have to acknowledge my great obligation 

 to my friend Mr. H. W. Bates, the well-known author 

 of the ' Naturalist on the River Amazons,' who has 

 given me his advice and assistance in the prep)aration 

 of my journals for publication ; and to another valued 

 friend, Mr. George Bishop, under whose hospitable 

 roof, on the banks of the Thames at Twickenham, 

 the greater part of the present volume has been 

 prepared for the press. 



