PREFACE. 



THE following Memoir has been undertaken at the 

 urgent solicitation of friends. Dreading the temptations 

 to partial and therefore untruthful representation, to 

 which relatives are exposed in attempting to portray the 

 character of the objects of their love, I at first resolutely 

 declined to be the Biographer of my brother. It was only 

 when one to whom the public instinctively looked with 

 hope, the Rev. Dr. Cairns, expressed reluctantly, but 

 decisively, his inability to undertake the task, that my 

 scruples were overcome ; and the result is now before the 

 reader. 



While an honest and earnest attempt has been made 

 throughout after truthful simplicity of narration, all ex- 

 pression of personal opinion has been as far as possible 

 avoided. In fact, the mass of letters at my disposal has 

 made the Life in great part an autobiography. 



I have to acknowledge, with much gratitude, assistance 

 received from the scientific friends whose names appear as 

 contributors to the volume, and also the great kindness 

 with which they and others have placed letters and private 

 papers freely at my service. 



b 



