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slightly heated and the rods of ice withdrawn from them 
and placed on two supports eight and a half inches 
apart, and a weight of one pound hung from the 
centre of these ice beams. The beams at once began 
bending and continued bending so long as the weights were 
left on them, thus proving the viscosity of the ice experi- 
mented on. The ice of these beams though similar was 
not the same as glacier ice; other ice beams were there- 
fore made, in as close imitation of glacier ice as possible, 
which was done by placing a small quantity of water in 
the tubes, then some snow, and pressing it firmly to the 
bottom of the tubes, then adding more snow, and again 
firmly pressing it down, and so on till the tubes were 
filled, as much pressure being applied as possible to the 
snow to drive out the water. The tubes were then placed 
for some time in the freezing mixture. The ice beams 
were afterwards withdrawn from the tubes and placed on 
the supports, and a weight of one pound hung from the 
centre. The beams of snow ice so made were found to 
be more easily bent than those made from the water, The 
rate at which they bent varied, possibly owing to there 
being more or less water-ice mixed with the snow-ice: 
one of the beams bent one inch in five minutes. Tem- 
perature seemed to have some influence on the rate of 
bending of these beams, but this point was difficult to 
determine on account of the different beams bending at 
different rates at the same temperature ; but so far as 
could be ascertained from the experiments, the beams 
bent slower the lower the temperature. The lowest tem- 
perature used in these experiments was rather more than 
three Fahrenheit degrees below freezing. 
Smaller rods of snow-ice were then made ‘2-inch in 
diameter, and as it was found that these could be easily 
bent in the hand, it was thought possible to bend them 
into rings. In attempting to bend these rods round a 
cylinder three inches in diameter, a difficulty was met 
with, After the pressure had been applied a short 
time, and before the circle was half turned, the 
rods always broke with a pressure which they 
easily bore at the beginning. Here, then, was 
a difficulty, The explanation seemed to fail at the last 
moment. The bending had so altered the structure of 
the ice, that it had lost much of its viscosity and become 
brittle. How then are we to account for glacier ice 
keeping its viscosity after years of bending. On exa- 
mining the fracture of the beams it appeared as if a 
fibrous structure had been developed in the ice by the 
bending. The fracture did not go straight across, but 
part of it ran parallel with the axis of the beam, strongly 
resembling the fracture of poor bar iron, crystalline at 
one part, fibrous at another. The bending of the ice had 
evidently developed a laminated structure in it, similar to 
that found in glaciers. This laminated structure was 
developed along the beams, as was to be expected ; for the 
direction in which this structure will be developed depends 
more on the direction in which the particles of ice are 
caused to slip over each other, than on the direction in 
which the pressure or tension is applied. The bending 
having produced this laminated structure in the ice, it 
is evident that the beams will be weaker after this 
structure is developed than before, on account of the 
cohesion of the ice being weakened along the planes of 
lamination. It was thought therefore that if the pressure 
was taken off the ice so as to relieve the particles from 
strain and stop them sliding over each other, that the 
laminz which had been developed in the ice, would, so 
to speak, become welded together, and the strength and 
plasticity of the beam be restored. Acting on this sup- 
position an attempt was again made to bend the ice-beam 
into acircle. After a small part of the circle had been 
turned, the pressure was taken off the beam and a 
short time given for the particles to rearrange them- 
selves; the pressure was then again applied, a small 
part more bent and so on, When done in this way 
a ee eee 
it was found that the ice-beams were easily bent - 
into a circle, the ends were then united by means of pres- 
sure, and a solid ring was thus produced from a straight 
beam of ice. These conditions of alternate rest and 
pressure are in all probability those which exist in glaciers. 
After pressure has acted at one part of the glacier, bend- 
ing takes place, so relieving the ice at that part from the 
pressure, which comes to bear on another part of the 
glacier ; and before the pressure again comes to bear 
on the first part its strength and plasticity or viscosity 
has been restored by rest. 
Although ice under certain conditions has by these ex- 
periments been shown to be a viscous substance, to have 
the power of changing its shape and so enabling it to 
flow—though slowly—in its channel; although it has 
thus been shown that the viscosity of ice is a cause of 
glacier motion, yet it must not, therefore, be concluded 
that it is the only cause. Among other causes which 
may assist in producing glacier motion may be men- 
tioned; 1st. The sliding of the ice over its channel ; this 
sliding being assisted by the tendency which the ice has 
to melt where it rests on its channel. znd. The melting 
of the ice in front of obstacles, the melting being produced 
by the melting point of the ice in contact with the 
obstacle being lowered by the pressure of the ice behind. 
3rd. The melting of the ice in the body of the glacier, by 
heavy pressure being brought to bear at certain points, 
part of the water so formed finding its way to the channel 
under the ice, and part being re-frozen. 4th. The cre- 
vasses in the glacier formed by the fracture of the ice. 
This breaking up of the ice will enable large masses of 
ice to move into different positions relatively to each 
other, much more easily than if the ice was solid. This 
breaking up of the ice will also make the motion due to 
its viscosity take place quicker than if the ice was in one 
mass, 5th. The old dilatation theory explains some- 
thing of the motion of glaciers, though it may not explain 
how that motion takes place, yet it accounts for some of 
the pressure which produces that motion. 
JoHN AITKEN 
SUB-WEALDEN EXPLORATION 
S {NCE the last quarterly report, troublesome accidents 
have delayed this undertaking. On the very day of 
the meeting in Jermyn Street in December last, the drill- 
ing tool broke off close to the edge, leaving a flat chisel 
(9 in. wide tapering up to 2 in.) at the bottom of the bore. 
A fortnight was lost in the endeavour to extract it. Mr. 
Bosworth’s ingenuity and patience were sorely tried ; but 
he at last succeeded in bringing it to the top from a depth 
of about 96 ft. 34 {t. consisting of narrow bands of cal- 
careous shale, alternating with argillaceous limestone in 
layers of from 4 to 6in. were passed through; but on 
January 28, at 131 ft, from the surface, a bed of pure solid 
white gypsum 4 ft. in thickness, was reached and per- 
forated, the new trifid drilling tool bringing up solid 
cores. This is the first time a bed of gypsum of this 
character has been found in Sussex, and it probably indi- 
cates the presence of the Purbeck beds. If so, strata 
hitherto unknown to exist in Sussex are now added to 
our geological information, and the scientific world will 
have its interest re-awakened to this, the first boring 
attempted in England for purely scientific purposes, 
Boring is a tedious and expensive process, and we hear 
that the preliminary cost of machinery has exhausted the 
treasury. Subscriptions are earnestly requested to com- 
plete the second sum of 1000/. promised on condition 
that 2000/. be raised. Mr. Henry Willett, Arnold House, 
Brighton, will be pleased to receive any sums for the’ 
purpose, It would be a great disaster indeed if the boring 
had to be stopped for want of funds ; but we feel sure that 
when the state of matters is made known to the friends of 
science Mr, Willett will soon have to reporta full treasury. 
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