ied on a series of investigations at the Roman Villa discovered on his land at Abinger； Darwin's son William examined for his father the evidence at Beaulieu Abbey； Brading； Stonehenge and other localities in the neighbourhood of his home； his sons Francis and Horace were enlisted to make similar enquiries at Chideock and Silchester； while Francis Galton contributed facts noticed in his walks in Hyde Park。 By correspondence with Fritz Muller and Dr Ernst； Darwin obtained information concerning the worm…casts found in South America； from Dr Kreft those of Australia； and from Mr Scott and Dr （afterwards Sir George） King； those of India； the last…named correspondent also supplied him with much valuable information obtained in the South of Europe。 Help too was obtained from the memoirs on Earthworms published by Perrier in 1874 and van Hensen in 1877； while Professor Ray Lankester supplied important facts with regard to their anatomy。
When therefore the series of interesting monographs on plant…life had been completed； Darwin set to work in bringing the information that he had gradually accumulated during forty…four years to bear on the subject of his early paper。 He also utilised the skill and ingenuity he had acquired in botanical work to aid in the elucidation of many of the difficulties that presented themselves。 I well remember a visit which I paid to Down at this period。 At the side of the little study stood flower…pots containing earth with worms； and； without interrupting our conversation； Darwin would from time to time lift the glass plate covering a pot to watch what was going on。 Occasionally； with a humorous smile； he would murmur something about a book in another room； and slip away； returning shortly； without the book but with unmistakeable signs of having visited the snuff…jar outside。 After working about a year at the worms； he was able at the end of 1881 to publish the charming little book〃The Formation of Vegetable Mould through the Action of Worms； with Observations on their Habits〃。 This was the last of his books； and its reception by reviewers and the public alike afforded the patient old worker no little gratification。 Darwin's scientific career； which had begun with geological research； most appropriately ended with a return to it。
It has been impossible to sketch the origin and influence of Darwin's geological work without； at almost every step； referring to the part played by Lyell and the 〃Principles of Geology〃。 Haeckel； in the chapters on Lyell and Darwin in his 〃History of Creation〃； and Huxley in his striking essay 〃On the Reception of the Origin of Species〃 （〃L。L。〃 II。 pages 179… 204。） have both strongly insisted on the fact that the 〃Origin〃 of Darwin was a necessary corollary to the 〃Principles〃 of Lyell。
It is true that； in an earlier essay； Huxley had spoken of the doctrine of Uniformitarianism as being； in a certain sense； opposed to that of Evolution （Huxley's Address to the Geological Society； 1869。 〃Collected Essays〃； Vol。 VIII。 page 305； London； 1896。）； but in his later years he took up a very different and more logical position； and maintained that 〃Consistent uniformitarianism postulates evolution as much in the organic as in the inorganic world。 The origin of a new species by other than ordinary agencies would be a vastly greater 'catastrophe' than any of those which Lyell success fully eliminated from sober geological speculation。〃 （〃L。L。〃 II。 page 190。）
Huxley's admiration for the 〃Principles of Geology〃； and his conviction of the greatness of the revolution of thought brought about by Lyell； was almost as marked as in the case of Darwin himself。 （See his Essay on 〃Science and Pseudo Science〃。 〃Collected Essays〃； Vol。 V。 page 90； London； 1902。） He felt； however； as many others have done； that in one respect the very success of Lyell's masterpiece has been the reason why its originality and influence have not been so fully recognised as they deserved to be。 Written as the book was before its author had arrived at the age of thirty； no less than eleven editions of the 〃Principles〃 were called for in his lifetime。 With the most scrupulous care； Lyell； devoting all his time and energies to the task of collecting and sifting all evidence bearing on the subjects of his work； revised and re…revised it； and as in each edition； eliminations； modifications； corrections； and additions were made； the book； while it increased in value as a storehouse of facts； lost much of its freshness； vigour and charm as a piece of connected reasoning。
Darwin undoubtedly realised this when he wrote concerning the 〃Principles〃； 〃the first edition； my old true love； which I never deserted for the later editions。〃 （〃M。L。〃 II。 page 222。） Huxley once told me that when； in later life； he read the first edition； he was both surprised and delighted； feeling as if it were a new book to him。 （I have before me a letter which illustrates this feeling on Huxley's part。 He had lamented to me that he did not possess a copy of the first edition of the 〃Principles〃； when； shortly afterwards； I picked up a dilapidated copy on a bookstall； this I had bound and sent to my old teacher and colleague。 His reply is characteristic：
October 8； 1884。
My Dear Judd；
You could not have made me a more agreeable present than the copy of the first edition of Lyell； which I find on my table。 I have never been able to meet with the book； and your copy is； as the old woman said of her Bible； 〃the best of books in the best of bindings。〃
Ever yours sincerely；
T。H。 Huxley。
I cannot refrain from relating an incident which very strikingly exemplifies the affection for one another felt by Lyell and Huxley。 In his last illness； when confined to his bed； Lyell heard that Huxley was to lecture at the Royal Institution on the 〃Results of the 'Challenger' expedition〃： he begged me to attend the lecture and bring him an account of it。 Happening to mention this to Huxley； he at once undertook to go to Lyell in my place； and he did so on the morning following his lecture。 I shall never forget the look of gratitude on the face of the invalid when he told me； shortly afterwards； how Huxley had sat by his bedside and 〃repeated the whole lecture to him。〃）
Darwin's generous nature seems often to have made him experience a fear lest he should do less than justice to his 〃dear old master；〃 and to the influence that the 〃Principles of Geology〃 had in moulding his mind。 In 1845 he wrote to Lyell； 〃I have long wished； not so much for your sake； as for my own feelings of honesty； to acknowledge more plainly than by mere reference； how much I geologically owe you。 Those authors； however； who like you； educate people's minds as well as teach them special facts； can never； I should think； have full justice done them except by posterity； for the mind thus insensibly improved can hardly perceive its own upward ascent。〃 （〃L。L。〃 I。 pages 337…8。） In another letter； to Leonard Horner； he says： 〃I always feel as if my books came half out of Lyell's brain； and that I never acknowledge this sufficiently。〃 （〃M。L。〃 II。 page 117。） Darwin's own most favourite book； the 〃Narrative of the Voyage〃； was dedicated to Lyell in glowing terms； and in the 〃Origin of Species〃 he wrote of 〃Lyell's grand work on the 〃Principles of Geology〃； which the future historian will recognise as having produced a revolution in Natural Science。〃 〃What glorious good that work has done〃 he fervently exclaims on another occasion。 （〃L。L。〃 I。 page 342。）
To the very end of his life； as all who were in the habit of talking with Darwin can testify； this sense of his indebtedness to Lyell remained with him。 In his 〃Autobiography〃； written in 1876； the year after Lyell's death； he spoke in the warmest terms of the value to him of the 〃Principles〃 while on the voyage and of the aid afforded to him by Lyell on his return to England。 （〃L。L。〃 I。 page 62。） But the year before his own death； Darwin felt constrained to return to the subject and to place on record a final appreciationone as honourable to the writer as it is to his lost friend：
〃I saw more of Lyell than of any other man； both before and after my marriage。 His mind was characterised； as it appeared to me； by clearness； caution； sound judgment； and a good deal of originality。 When I made any remark to him on Geology； he never rested until he saw the whole case clearly； and often made me see it more clearly than I had done before。 He would advance all possible objections to my suggestion； and even after these were exhausted would remain long dubious。 A second characteristic was his hearty sympathy with the work of other scientific men。。。His delight in science was ardent； and he felt the keenest interest in the future progress of mankind。 He was very kind…hearted。。。His candour was highly remarkable。 He exhibited this by becoming a convert to the Descent theory； though he had gained much fame by opposing Lamarck's views； and this after he had grown old。〃
〃THE SCIENCE OF GEOLOGY IS ENORMOUSLY INDEBTED TO LYELLMORE SO； AS I BELIEVE； THAN TO ANY OTHER MAN WHO EVER LIVED。〃 （〃L。L。〃 I。 pages 71…2 （the italics are mine。）
Those who knew Lyell intimately will recognise the truth of the portrait drawn by his dearest friend； and I believe that posterity will endorse Darwin's deliberate verdict concerning the value of his labours。
It was my own good fortune； to be brought into close contact with these two great men during the later years of their life； and I may perhaps be permitted to put on record the impressions made upon me during friendly intercourse with both。
In some respects； there was an extraordinary resemblance in their modes and habits of thought； between Lyell and Darwin； and this likeness was also seen in their modesty； their deference to the opinion of younger men； their enthusiasm for science； their freedom from petty jealousies and their righteous indignation for what was mean and unworthy in others。 But yet there was a difference。 Both Lyell and Darwin were cautious； but perhaps Lyell carried his caution to the verge of timidity。 I think Darwin possessed； and Lyell lacked； what I can only describe by the theological term； 〃faiththe substance of things hoped for； the evidence o