After some failures and many interruptions, the boring was carried to the depth of 1114 feet, and the cores obtained were sent to England. Here the examination of the materials was fortunately undertaken by a zoologist of the highest repute, Dr G.J. Hinde--who has a wide experience in the study of organisms by sections--and he was aided at all points by specialists in the British Museum of Natural History and by other naturalists. Nor were the chemical and other problems neglected.
The verdict arrived at, after this most exhaustive study of a series of cores obtained from depths twice as great as that thought necessary by Darwin, was as follows:--"The whole of the cores are found to be built up of those organisms which are seen forming coral-reefs near the surface of the ocean--many of them evidently in situ; and not the slightest indication could be detected, by chemical or microscopic means, which suggested the proximity of non-calcareous rocks, even in the lowest portions brought up."
But this was not all. Professor David succeeded in obtaining the aid of a very skilful engineer from Australia, while the Admiralty allowed Commander F.C.D. Sturdee to take a surveying ship into the lagoon for further investigations. By very ingenious methods, and with great perseverance, two borings were put down in the midst of the lagoon to the depth of nearly 200 feet. The bottom of the lagoon, at the depth of 101 1/2 feet from sea- level, was found to be covered with remains of the calcareous, green sea- weed Halimeda, mingled with many foraminifera; but at a depth of 163 feet from the surface of the lagoon the boring tools encountered great masses of coral, which were proved from the fragments brought up to belong to species that live within AT MOST 120 feet from the surface of the ocean, as admitted by all zoologists. ("The Atoll of Funafuti; Report of the Coral Reef Committee of the Royal Society", London, 1904.)
Darwin's theory, as is well known, is based on the fact that the temperature of the ocean at any considerable depth does not permit of the existence and luxuriant growth of the organisms that form the reefs. He himself estimated this limit of depth to be from 120 to 130 feet; Dana, as an extreme, 150 feet; while the recent very prolonged and successful investigations of Professor Alexander Agassiz in the Pacific and Indian Oceans lead him also to assign a limiting depth of 150 feet; the EFFECTIVE, REEF-FORMING CORALS, however, flourishing at a much smaller depth. Mr Stanley Gardiner gives for the most important reef-forming corals depths between 30 and 90 feet, while a few are found as low as 120 feet or even 180 feet.
It will thus be seen that the verdict of Funafuti is clearly and unmistakeably in favour of Darwin's theory. It is true that some zoologists find a difficulty in realising a slow sinking of parts of the ocean floor, and have suggested new and alternative explanations: but geologists generally, accepting the proofs of slow upheaval in some areas-- as shown by the admirable researches of Alexander Agassiz--consider that it is absolutely necessary to admit that this elevation is balanced by subsidence in other areas. If atolls and barrier-reefs did not exist we should indeed be at a great loss to frame a theory to account for their absence.
After finishing his book on Coral-reefs, Darwin made his summer excursion to North Wales, and prepared his important memoir on the glaciers of that district: but by October (1842) we find him fairly settled at work upon the second volume of his "Geology of the 'Beagle'--Geological Observations on the Volcanic Islands, visited during the Voyage of H.M.S. 'Beagle'". The whole of the year 1843 was devoted to this work, but he tells his friend Fox that he could "manage only a couple of hours per day, and that not very regularly." ("L.L." I. page 321.) Darwin's work on the various volcanic islands examined by him had given him the most intense pleasure, but the work of writing the book by the aid of his notes and specimens he found "uphill work," especially as he feared the book would not be read, "even by geologists." (Loc. cit.)
As a matter of fact the work is full of the most interesting observations and valuable suggestions, and the three editions (or reprints) which have appeared have proved a most valuable addition to geological literature. It is not necessary to refer to the novel and often very striking discoveries described in this well-known work. The subsidence beneath volcanic vents, the enormous denudation of volcanic cones reducing them to "basal wrecks," the effects of solfatarric action and the formation of various minerals in the cavities of rocks--all of these subjects find admirable illustration from his graphic descriptions. One of the most important discussions in this volume is that dealing with the "lamination" of lavas as especially well seen in the rocks of Ascension. Like Scrope, Darwin recognised the close analogy between the structure of these rocks and those of metamorphic origin--a subject which he followed out in the volume "Geological Observations on South America".
Of course in these days, since the application of the microscope to the study of rocks in thin sections, Darwin's nomenclature and descriptions of the petrological characters of the lavas appear to us somewhat crude. But it happened that the "Challenger" visited most of the volcanic islands described by Darwin, and the specimens brought home were examined by the eminent petrologist Professor Renard. Renard was so struck with the work done by Darwin, under disadvantageous conditions, that he undertook a translation of Darwin's work into French, and I cannot better indicate the manner in which the book is regarded by geologists than by quoting a passage from Renard's preface. Referring to his own work in studying the rocks brought home by the "Challenger" (Renard's descriptions of these rocks are contained in the "Challenger Reports". Mr Harker is supplementing these descriptions by a series of petrological memoirs on Darwin's specimens, the first of which appeared in the "Geological Magazine" for March, 1907.), he says:
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- 1event in this quiet retired corner of the world; and nearly
- 2he scrambled up to the top, and presently found himself
- 3ray of an electric torch down into the darkness beneath
- 4Mounting the steps to the raised writing-table, he rested
- 5before. For what was he waiting, or for whom? He heard
- 6One Chinaman more or less does not make any very great
- 7“I heard a shriek like nothing I ever heard in my life.
- 8of Cohen, remained to be proved. Certain critics have declared
- 9steps were ahead of him, and then a long brick tunnel in
- 10Remembering that the premises almost overhung the Thames,
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- reason to believe her dead, and that it was because of
- the building. He thought he had detected something, and
- wide with terror and her gaze set upon him across the room.
- legality or otherwise of his foreign relations evidently
- In the afternoon we paid our respects to the governor —
- moved them aside systematically, one after another, seeking
- post as a stepping-stone, he succeeded in wedging his foot
- as the light came nearer and nearer, he discerned Ah Fu,
- the gunpowder was wanted for making a noise on their saint
- that the dead Chinaman had been in negotiation with Huang