0 feet; a
drum, 10,560 feet; music, a strong brass band, 15,840 feet; very heavy
cannonading, 575,000 feet, or 90 miles. In the Arctic regions
conversation has been maintained over water a distance of 6,766 feet. In
gases the velocity of sound increases with the temperature; in air this
increase is about two feet per second for each degree centigrade. The
velocity of sound in oxygen gas at zero C. is 1,040 feet; in carbonic
acid, 858 feet; in hydrogen, 4,164 feet. In 1827 Colladon and Sturm
determined experimentally the velocity of sound in fresh water; the
experiment was made in the Lake of Geneva, and it was found to be 4,174
feet per second at a temperature of 15 degrees C. The velocity of sound
in alcohol at 20 degrees C. is 4,218 feet; in ether at zero, 3,801; in
sea water at 20 degrees C., 4,768. By direct measurements, carefully
made, by observing at night the interval which elapses between the flash
and report of a cannon at a known distance, the velocity of sound has
been about 1,090 per second at the temperature of freezing water.

DESCRIPTION OF THE YELLOWSTONE PARK.--The Yellowstone National Park
extends sixty-five miles north and south, and fifty-five miles east
and west, comprising 3,575 square miles, and is all 6,000 feet or more
above sea-level. Yellowstone Lake, twenty miles by fifteen, has an
altitude of 7,788 feet. The mountain ranges which hem in the valleys
on every side rise to the height of 10,000 to 12,000 feet, and are
always covered with snow. This great park contains the most striking
of all the mountains, gorges, falls, rivers and lakes in the whole
Yellowstone region. The springs on Gardiner's River cover an area of
about one square mile, and three or four square miles thereabout are
occupied by the remains of springs which have ceased to flow. The
natural basins into which these springs flow are from four to six feet
in diameter and from one to four feet in depth. The principal ones are
located upon terraces midway up the sides of the mountain. The banks
of the Yellowstone River abound with ravines and canons, which are
carved out of the heart of the mountains through the hardest of rocks.
The most remarkable of these is the canon of Tower Creek and Column
Mountain. The latter, which extends along the eastern bank of the
river for upward of two miles, is said to resemble the Giant's
Causeway. The canon of Tower Creek is about ten miles in length and
is so deep and gloomy that it is called