gh mountain" occupies a large portion of the
central and southern part of the island of Hawaii, and reaches an
elevation of 13,760 feet. It has been built up by lavas thrown out in a
highly fluid state, and flowing long distances before cooling; as a
consequence the slopes of the mountain are very gentle, averaging,
according to Prof. Dana, not more than six and a half degrees. Its
craters are numerous, and usually occur near the summit and on the
sides, new ones opening frequently, and furnishing, as in the latest
instance, magnificent lava streams. The terminal crater is circular,
8,000 feet in diameter, and in 1864 was about 1,000 feet deep. In 1859
an enormous lava fountain spouted from this crater for four or five
days, throwing a column of white hot fluid lava about 200 feet in
diameter to the height of two or three hundred feet. The lava stream ran
50 miles to the sea in eight days. Other great eruptions have occurred
in 1832, 1840, 1843, 1852, 1855, 1868 and 1873. The lava streams poured
out in 1840, 1859, and 1868, flowed to the sea, adding considerably to
the area of the island. Those of 1843 and 1855 are estimated to have
poured out respectively 17,000,000,000 and 38,000,000,000 cubic feet of
lava. In 1868 the lava stream forced its way under ground a distance of
twenty miles, and burst forth from a fissure two miles long, throwing up
enormous columns of crimson lava and red hot rock to the height of five
or six hundred feet.

On the eastern part of Mauna Loa, 16 miles from the summit crater, is
Kilauea, the largest continuously active crater in the world. It is
eight miles in circumference, and 1,000 feet deep. Its eruptions are
generally independent of those of Mauna Loa.

* * * * *

NEW AIR ENGINE.

A valuable improvement in compressed air engines has recently been
patented in this country and in Europe by Col. F. E. B. Beaumont, of the
Royal Engineers, and we learn from accounts given in the London and
provincial papers that it has proved highly efficient and satisfactory.

The engine possesses some peculiar features which render it very
economical in the use of compressed air. It has two cylinders, one being
much larger than the other. Into the smaller of these cylinders the
compressed air is taken directly from the reservoir, and after doing its
work there it is discharged into the larger cylinder, where it is
further expanded, being finally discharged into th