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even only a few inches.  And as we might expect, perfect silence attends the downward slipping of the gigantic mass.  The motion is, I believe, sufficiently explained as a skating motion.  The skate is, however, fixed, the ice moves.  The great Aletsch Glacier collects its snows among the highest summits of the Oberland.  Thence, the consolidated ice makes its way into the Rhone Valley, travelling a distance of some 20 miles.  The ice now melting into the youthful Rhone fell upon the Monch, the Jungfrau or the Eiger in the days when Elizabeth ruled in England and Shakespeare lived.

The ice-fall is a common sight on the glacier.  In great lumps and broken pinnacles it topples over some rocky obstacle and falls shattered on to the glacier below.  But a little further down the wound is healed again, and regelation has restored the smooth surface of the glacier.  All such phenomena are explained on James Thomson’s exposition of the behaviour of a substance which expands on passing from the liquid to the solid state.

We thus have arrived at very far-reaching considerations arising out of skating and its science.  The tendency for snow to accumulate on the highest regions of the Earth depends on principles which we cannot stop to consider.  We know it collects above a certain level even at the Equator.  We may consider, then, that but for the operation of the laws which James Thomson brought to light, and which his illustrious brother,

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Lord Kelvin, made manifest, the uplands of the Earth could not have freed themselves of the burthen of ice.  The geological history of the Earth must have been profoundly modified.  The higher levels must have been depressed; the general level of the ocean relatively to the land thereby raised, and, it is even possible, that such a mean level might have been attained as would result in general submergence.

During the last great glacial period, we may say the fate of the world hung on the operation of those laws which have concerned us throughout this lecture.  It is believed the ice was piled up to a height of some 6,000 feet over the region of Scandinavia.  Under the influence of the pressure and fusion at points of resistance, the accumulation was stayed, and it flowed southwards the accumulation was stayed, and it flowed southwards over Northern Europe.  The Highlands of Scotland were covered with, perhaps, three or four thousand feet of ice.  Ireland was covered from north to south, and mighty ice-bergs floated from our western and southern shores.

The transported or erratic stones, often of great size, which are found in many parts of Ireland, are records of these long past events:  events which happened before Man, as a rational being, appeared upon the Earth.

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A SPECULATION AS TO A PREMATERIAL UNIVERSE [1]

“And therefore...these things likewise had a birth; for things which are of mortal body could not for an infinite time back... have been able to set at naught the puissant strength of immeasurable age.”—­LUCRETIUS, De Rerum Natura.