Some of the incidents of his Cambridge life which he records are full of interest in their bearing on his future career. Foremost among them stands the friendship which he formed with Professor Henslow, whose lectures on botany he attended. He joined in the class excursions and found them delightful. But still more profitable to him were the long and almost daily walks which he enjoyed with his teacher, during the latter half of his time at Cambridge. Henslow's wide range of acquirement, modesty, unselfishness, courtesy, gentleness, and piety, fascinated him and exerted on him an influence which, more than anything else, tended to shape his whole future life. The love of travel which had been kindled by his boyish reading, now took a deeper hold of him as he read Humboldt's "Personal Narrative" and Herschel's "Introduction to the Study of Natural Philosophy." He determined to visit Teneriffe, and even went so far as to inquire about ships. But his desire was soon to be gratified in a far other and more comprehensive voyage. At the close of his college life he was fortunate enough, through Henslow's good offices, to accompany Sedgwick in a geological excursion in North Wales. There can be little doubt that this short trip sufficed to efface the dislike of geology which he had conceived at Edinburgh, and to show him how much it was in his own power to increase the sum of geological knowledge. To use his own phrase, he began to "work like a tiger" at geology. But he now had reached the main turning-point of his career. On returning home from his ramble with Sedgwick he found a letter from Henslow, telling him that Captain Fitz-Roy, who was about to start on the memorable voyage of the Beagle, was willing to give up part of his own cabin to any competent young man who would volunteer to go with him, without pay, as a naturalist. The post was offered to Darwin and, after some natural objections on the part of his father, accepted. The Beagle weighed anchor from Plymouth on December 27, 1831, and returned on October 2, 1836.