Marcu 12, 1914] 
NATURE 31 
LEREBRES -TO) THE EDITOR. 
[The Editor does not hold himself responsible for 
opinions expressed by his correspondents. Neither 
can he undertake to return, or to correspond with 
the writers of, rejected manuscripts intended for 
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taken of anonymous communications. ] 
Alexander Agassiz and the Funafuti Boring. 
Pror. Poutton has directed attention (NATURE, 
February 26, p: 712) to the fact that ‘‘very little has 
been said’? concerning the evidence on coral-reef 
formation obtained by the boring at Funafuti, and he 
also refers to the views upon the subject held by the 
late Prof. Alexander Agassiz. 
It will be remembered that the very successful 
borings at’ Funafuti were carried out by Profs. Sollas 
and Edgeworth David, and their assistants, under 
the auspices of the Royal Society, with valuable aid 
from the Admiralty and the Government of New South 
Wales. The place for the experiment was selected by 
a committee of the Royal Society, on which every 
shade of theoretical opinion was represented, this 
committee having the invaluable assistance of the late 
Admiral Wharton, who recommended Funafuti as 
perhaps the most typical atoll that could be found on 
the globe. 
The very complete set of cores, with all the other 
materials obtained during these borings, were, by the 
permission of the Board of Education, received in the 
geological laboratories of the Royal College of Science 
at South Kensington, where they were studied by the 
members of the staff, with the invaluable assistance 
of Dr. G. J. Hinde, much aid being also given by 
the officials of the British Museum (Natural History) 
and of the Geological Survey. 
Those who were responsible for the preparation of 
the report on the undertaking, published by the Royal 
Society in 1904, felt it to be outside their duty to 
advocate any particular theory of the origin of coral- 
reefs; their aim was simply to place on record the 
evidence obtained; and it may be added that this 
evidence is always open to examination and criticism 
from the circumstance that the halves of all the cores 
are now deposited in the British Museum, with the 
sections and other specimens, while duplicate halves 
of the cores have been sent to Sydney University. 
During the eight years that the work of studying 
the materials from Funafuti was in progress, I re- 
ceived many visits from my friend, Prof. Alexander 
Agassiz, and gladly profited by his advice and sugges- 
tions. He showed his confidence in the manner in 
which the work was being carried on by entrusting 
to me the materials he collected from the upraised 
coral-reefs of the Pacific, with the request to have 
them examined side by side with the Funafuti cores, 
the result being published at his own expense. 
I should not be justified in trying to reproduce the 
views of Agassiz as communicated to me in our fre- 
quent friendly discussions—everyone who knew him 
will accept my statement that they were always 
candidly and fairly expressed. But, fortunately, in 
the work published since his death, his position in the 
controversy is very clearly indicated. His own re- 
searches had demonstrated that, over very consider- 
able areas in the Pacific, elevation, often to the extent 
of rooo ft. or more, had taken place. Agassiz main- 
tained that the masses of coral-limestone in the up- 
raised islands—which were much altered, like the 
limestones in the lower part of the Funafuti boring— 
were Tertiary rocks, and that the lower cores of 
Funafuti were of the same age. His views are very 
clearly illustrated in a diagram reproduced in the 
, their relation to the views of others, as understood 
| by himself. 
_ I may add that the most careful study of the Funa- 
| futi limestones did not supply any evidence of such a 
change in the fauna as would justify their being 
assigned to any of the Tertiary periods. But even if 
such evidence had been found, the geologist would 
have been justified in arguing that this would only 
prove that subsidence had taken place with extreme 
slowness, or had been subjected to long interruptions. 
On the other hand, the fact, which Agassiz so fully 
demonstrated, that certain areas in the Pacific have 
undergone elevation in recent times, would suggest to 
every geologist, taking into account what we know 
of ‘‘the warping of the earth’s crust,” that other areas 
must simultaneously have been undergoing subsi- 
dence, and this was the view maintained by Darwin. 
We are entitled then to say that a boring, initiated 
and carried out under the direction of representatives 
of all the rival theories on coral-reef formation, was 
attended with brilliant success. In an island selected 
as a very typical atoll, the main boring was carried 
down more than goo ft. below the lowest depth at 
which, as all naturalists agree, reef-forming corals 
-ean flourish. The materials from top to bottom 
yielded only those organisms that thrive near the 
surface of the ocean, often in the position of 
growth. In opposition to the view that the 
boring may have penetrated only a talus on the 
side of the reef, it must be pointed out that two addi- 
tional borings were made in the very centre of the 
lagoon, which revealed, down to the depth of roo ft. 
below their limit of growth, the same reef-forming 
corals. Finally, in this very typical atoll, all idea of 
solution going on at the bottom of the lagoon was 
negatived by the luxuriant masses of the delicate 
calcareous alga, Halimeda, which, with the thinnest 
shelled Foraminifera, everywhere abounded in a per- 
fectly uncorroded state. 
With Prof. Poulton, then, we may fairly say that 
while the theory of subsidence is not of ‘‘ universal 
application ’’—and Darwin in all his later writings 
| candidly admitted that such was the case—yet the 
‘validity’ of this theory of subsidence is fully estab- 
lished in the case of the only atoll in which the test by 
boring has been carried out. Joun W. Jupp. 
Kew, February 28. 
An X-Ray Absorption Band. 
For some time past I have been trying to make 
accurate comparisons of the intensities of the various 
orders of X-ray spectra reflected by crystals. The 
purpose of the inquiry is to make experimental tests 
of the theoretical discussions by Debye and Sommer- 
feld in relation to the influence of molecular motions 
upon reflecting power. Of some of their predictions 
I have found it easy to obtain confirmation which is 
at least roughly quantitative. For instance, the in- 
tensities of the higher order spectra are much more 
affected by rise of temperature than the lower, and 
the amount of the change is of the right order of 
magnitude; also rock salt and sylvine show greater 
changes than fluorspar. 
In one case, however, the results have been puzzling. 
The relative intensities of the spectra of the diamond 
at ordinary temperatures are quantities of much im- 
portance. Now the diamond which I use is a thin 
flake which intercepts only a fraction of the incident 
primary ray, a fraction which diminishes as the dia- 
mond is set at a greater angle to the primary beam in 
order to obtain the higher order reflections. It would 
appear, therefore, to be necessary to make allowance 
for this waste of reflection opportunities, a correction 
“‘Letters and Recollections,” p. 343, together with ; which would not be necessary in the case of the 
NGs 231 5,.VOL..92 | 
