in the University and army, his teachers, his friends, and his pupils, the vivid memory of his strenuous, short life of triumphant struggle against difficulties, of clear thinking, high living, noble effort, and of the beginnings of real achievement. For myself I can truly say that I never had a pupil for whom I had a more lively friendship, or one for whom I had a more certain assurance of a distinguished and honourable career. He was an excellent scholar in many fields; he could teach, he could study, and he could inspire; he had in no small measure sympathy, aspiration, and humour. He possessed the rare combination of practical wisdom in affairs with a strong zeal for the pursuit of truth; he was a magnificent worker; he kept his mind open to many interests; he had a wonderfully clear brain; a strong judgment and sound common-sense. I had confidently looked forward to his doing great things in his special field of investigation. How far he has already accomplished anything noteworthy in this book, I must leave it for less biassed minds to determine. But though I am perhaps over-conscious of how different this book is from what it might have been, I would never have agreed to set it before the public as a mere memorial of a promising career cut short, if I did not think that, even as it is, it will fill a little place in the literature of his subject. When he finally set out for the front he entrusted to me the completion of what he had written. I have done my best to fulfil the pledge which I then gave him, that should anything untoward befall him, I would see his book through the press.