96 ENGLISH MEN OF SCIENCE. [chai*. professional engagements, but more often from myself.” 40. “ Considerable power in earlier days of en¬ during mental fatigue and of taking up without difficulty a considerable range of subjects. Ex¬ ample :—I was for a little while, æt. seventeen to twenty, employed in teaching, and I contrived in my scanty intervals of leisure to read a very large quantity of Greek and Latin, and to become, without any external assistance, a very fair mathematician [my correspondent occupies a high official position, in which considerable mathe¬ matical knowledge is essential]. I learnt also Italian at this time.” 41. “I should say considerable, judging by the number of things I have been able to learn and to do since adult age.” 42. “I think considerable, in mind. Have commonly had it said of me that it was wonderful how I got through so much work. Father—Was well known as a hard-worker. Mother—A great reader ; taught herself Greek