f the glaciers in the Alps, called the
Mer de Glace, one clear day in summer, when I suffered so much from the
heat, although standing upon a sea of ice, that it was necessary to
carry an umbrella. In fact, during my stay there was a case of sunstroke
that occurred upon this same glacier. This intense heat during the day
melts the surface of the ice, which forms streams that run along on the
top of a glacier until they come to a crevasse or riffle in the ice
river, where they plunge down and become a part of the glacial stream
that is flowing underneath the ice.

The speed at which these ice streams flow varies greatly with the size
of the glacier as to width and depth and the steepness of the grade, and
many other conditions. In its movement the glacier is constantly bending
and freezing and being torn asunder by tensional strain, yielding and
liquefying at other points by pressure, only to freeze again when that
pressure is removed. This, taken in connection with the friction of the
great ice bowlders, produces a movement that is exceedingly complicated
in its actions and interactions.

According to Professor Tyndall's investigations, the most rapid movement
observed in the glaciers of Switzerland is thirty-seven inches per day
at the point of greatest movement. From this point each way the motion
gradually diminishes until it reaches the sides of the glacier, where
the motion is not more than two or three inches.

The great North American glaciers move at a much higher rate of speed.
We are indebted to Dr. G. Frederick Wright, author of "The Ice Age in
North America," who spent a month studying the Muir glacier in Alaska,
for many details concerning that great ice river. This glacier empties
into Muir Inlet, which is an offshoot of Glacier Bay. It is situated in
latitude 58 degrees 50 minutes and longitude 136 degrees 40 minutes west
of Greenwich. The bay into which this glacier empties is about thirty
miles long and from eight to twelve miles wide. This bay, with its great
glacier, has a setting of grand mountain peaks. I cannot do better than
to quote the words of Dr. Wright when he describes the location of this
glacier. Dr. Wright lived for a month in a tent on the edge of this bay,
a short distance below the face of the great glacier, where the icebergs
fell off every few minutes into the deep water.

He says: "To the south the calm surface of the bay opened outward into
Cross Sound twenty-five miles away. Th