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March 9, 185 1 | 
NATURE 
377 

holes. The author also remarked that he had suggested a glacial 
origin for the terminal curvature of the laminz of slate-rocks as 
earlytas 1849. Mr. Gwyn Jeffreys read extracts from a work 
published by the Rev. Mr. Hodgson in 1827, on the Natural 
History of Northumberland, in which these borings in limestone 
were referred to the action of snails. Mr. Jeffreys considered 
the foot to be the sole instrument employed by the boring Mol- 
lusca in excavating their burrows. He exhibited specimens of 
Lias from Lyme Regis perforated by Pho/as, and of hard lime- 
stone from Malta perforated by Zithodomus, and remarked, in 
connection with the notion that asperities on the shell might be 
boring agents, that the shell of Zithodomus is perfectly smooth. 
Prof. Ramsay mentioned that he had seen Ae/ices taken out of 
these holes at Tenby by Dr. Buckland, who believed that the 
snails effected the perforations by the agency of an acid. Mr. 
Charlesworth thought thatif somuch uncertainty could prevail upon 
such a subject, it threw great doubt upon some of the grandest 
generalisations of geology. He referred to the evidence con- 
nected with the glaciation of the Great Orme’s Head, in which 
the origin of the perforations under discussion was of much im- 
portance, Mr. Darbyshire maintaining that they were the work 
of Pholades, while Mr. Bonney asserted that they were produced 
by snails. In the same way the origin af the celebrated borings 
in the Temple of Jupiter Serapis might be disputed, and the 
generalisation founded upon it rendered doubtful. Mr. Charles- 
worth noticed the necessarily small proportion of borers to the 
whole snail population of Britain, and remarked especially upon 
the absence of perforations in the chalk districts. He considered 
that repeated observations were necessary before this snail- 
engineering could be admitted, and suggested a systematic course 
of experiments. Mr. Boyd Dawkins suggested that the carbonic 
acid exhaled by snails in respiration might act upon limestones, 
and remarked that chalk weathers too rapidly to preserve the 
excavations.—2. ‘‘On the probable Cause, Date, and Duration of 
the Glacial Epoch of Geology,” by Lieut.-Col. Drayson, R.A. 
In this paper the author started from the fact that the pole of 
the ecliptic could not be the centre of polar motion, as the pole 
yaried in its distance from that centre. He indicated the curve 
which the pole did trace, and this curve was such as to give for 
the date 13,000 B.c. a climate very cold in winter, and very hot 
in summer for each hemisphere. The duration of the glacial 
epoch he fixed at about 16,000 years. The calculations resulting 
from this movement were stated to agree accurately with observa- 
tion. Prof. Ramsay inquired whether the author’s theory in- 
volved the recurrence of glacial epochs, and whether he considered 
the course of phenomena to be constant in early astronomical 
epochs. Rev. Osmond Fisher inquired whether the theory was 
founded on observed facts, or whether it was a purely physical 
theory. He also asked whether the line representing the change 
in the direction of the pole formed a re-entering curve, and 
whether the theory would account for the climate of Greenland 
in Miocene times. He suggested changes in the form of the 
earth which must have affected the direction of its axis, The 
President remarked upon the difficulty that arose from astro- 
nomical theories differing so much among themselves. He 
referred particularly to Adhémar’s theory, and remarked that the 
difficulty connected with it is, that it invokes a recurrent cause, 
which must produce similar effects every 21,000 years, whilst 
there is very little evidence of glacial action during the whole 
long period of the Tertiary epoch. The author, in reply, 
stated that he could not go back beyond 30,000 years, but 
that he thought glacial conditions must recur. He had not 
astronomical data beyond 2, 500 years, and these were very yague. 
The motion would be the same in kind, but uncertain in 
degree. His theory was based entirely upon observed facts. In 
laying down the curve, he considered it safe to go as far as the 
semicircle, as he had observations covering 40°; but he caquld 
not say whether the curve would be a re-entering one, although 
it showed a tendency that way, and would certainly be very 
nearly so. With regard to the change of climate of Greenland, 
as evidenced by its Miocene flora, he was not sufficiently versed 
in botany ta pronounce an opinion. He remarked, in conclusion, 
that the distance of a planetary body from the sun did not seem 
to affect climate, and stated that Venus is at present suffering 
under a most severe glacial epoch. —3. ‘On Allophane and an 
allied Mineral found at Northampton,” by Mr. W. D. Her- 
man. In this paper the author gave analyses of an amorphous, 
translucent, reddish-yellow mineral, found incrusting sandstone 
in the ironstones of the Northampton sands, the comparison of 
which with Mr, Northcote’s analysis of allophane from Charlton 



leads him to infer the identity of the two minerals. He also 
noticed a soft white substance found in certain joints in a section 
of the Northampton sand, and also referred to allophane by the 
late Dr. Berrell, who analysed it. This substance was said to 
occurnot unfrequently inthe inferior oolite of the Midland Counties. 
By analysis, it was shown to agree nearly with Samoite and Halloy- 
site. Mr, David Forbes stated that he had found phosphoric acid in 
the first-mentioned mineral, which was perhaps the cause of its 
lustre. The mineral was probably not pure allophane. Prof. 
Morris suggested a chemical and microscopical examination ot 
the strata above the places in which these minerals occur, which 
would probably reveal the conditions under which they have been 
formed. They were probably produced by the decomposition of 
silicates in the overlying rocks during the percolation of water. 
This applied also to the Charlton locality. Mr. Carruthers men- 
tioned that allophane often fills the inflorescence of the Cycads 
of the Yorkshire Oolite, entirely destroying the vegetable structure, 
and that it also occurs in clay nodules from the coal-measures. 
Mr. Carruthers suggested that the decomposition of vegetable 
matter in clays might aid in the production of the mineral. 
— 4. “Notes on the Peat and underlying Beds observed in the 
construction of the Albert Dock, Hull,” by J. C. Hawkshaw, Esq , 
M.A., F.G.S. The Albert Dock is situated on the foreshore of 
the River Humber. The excavation for the dock extended over 
an area of about thirty acres, and they were carried down to a 
depth varying from 8 feet to 27 feet below low water of spring- 
tides. Beneath the more modern deposits of Humber silt a bed 
of peat, Hessle Clay, Hessle Sand, and purple clay, were suc- 
cessively met with. The peat was found at the west end of the 
Dock at the level of low water; at the east end the bed dipped 
so that the upper surface was found at eight feet below the level 
of low water. In the peat were found the remains of a fire, 
which the writer attributed to human agency. Oak-trees of 
large size were imbedded in the peat, some of which had grown 
where they were found, as was shown by the stools remaining 
with the roots penetrating the Boulder-clay beneath. In one 
oak-tree, five feet in diameter, a hole was found filled with acorns 
and nuts. Many of the nuts were broken open at the ends, and 
had evidently formed part of the store of a squirrel. Remains 
of Coleoptera were found, and one horn-core of a Bos. The 
excavation did not extend below the upper parts of the purple 
clay. Some of the borings, however, penetrated the chalk at a 
depth 85 feet below low water level, passing through a bed of 
sand 16 feet thick below the purple clay. Several thousand 
cubic yards of this sand were brought up into the foundations 
by springs of water which flowed up through old bore-holes. 
The abstraction of this sand from beneath the clay-bed caused 
it to subside many feet. The writer thinks that analogous 
subsidences may take place from natural causes ; for instance, 
where large springs occur in tidal rivers. Two sections 
exhibited showed the beds above the chalk for a distance of 
rather more than a mile along the foreshore. The Hessle 
Sand was shown to thin out to the westward. It does 
not, in the writer’s opinion, increase in thickness in that 
direction, as it was shown to do in a section already pub- 
lished in the Proceedings of the Society. The President re- 
marked upon the singularity of the occurrence of a bed of ashes 
at such a depth in these deposits. Mr. Gwyn Jeffreys referred to 
the President’s paper on the Kelsey Hill beds, and remarked on 
some of the mollusca obtained by Mr. Hawkshaw. Mr. Boyd 
Dawkins mentioned the occurrence of a submarine forest on the 
coast of Somersetshire, forming a layer of peat, beneath which 
was a land-surface, on which the forest had grown, and in which 
flint-flakes were found at Portlock and Watchet on digging 
through the peat, He remarked on the depression of the coast 
of Somersetshire within the human period, and suggested that 
the forest at Hull may have been contemporaneous with that of 
Somersetshire. Prof. Morris inquired whether any trees or roots 
were found as when growing. The shells obtained were estuarine. 
Prof. Morris remarked on a submerged forest near Whittlesey, 
with terrestrial plants and freshwater shells imbedded in the 
overlying clay, The author, in reply, stated that the trees had 
fallen where they grew. ‘The general appearance of things led 
him to the belief that the fire which had destroyed part of the 
forest was of human production. The following specimens were 
submitted to the meeting :—Specimens of Allophane, from the 
Northampton Sands; exhibited by Mr, F. V. Runler, f.G.S, 
Specimens of Websterite, from the junction of the Tertiaries and 
the Chalk, near Bromley, Kent, exhibited by Mr. W. Whitaker, 
F,G.S, Specimens from the Peat-beds at the Hull Albert 
