, with two ounces of marrow-bone, he placed the
vessel horizontally between the bars of the grate, about half-way into
the fire. In three minutes he found it raised to a great heat, and
perceiving the heat in a very short time become more raging, stepped
to a side-table for an iron to take the digester out of the fire,
when it suddenly burst with the explosion of a musket. It was heard at
a considerable distance, and actually shook the house. The bottom of
the vessel that was in the fire gave way; the blast of the expanded
water blew all the coals out of the fire into the room, the remainder
of the vessel flew across the room, and, hitting the leaf of an oak
table, an inch thick, broke it all in pieces, and rebounded half the
length of the room back again. He could not perceive the least sign of
water, though he looked carefully for it; the fire was quite
extinguished, and every coal black in an instant.

The following accident was attended with more fatal consequences.

A steam-engine was repairing at Chelsea, and, as the workmen were
endeavouring to discover the defect, the boiler suddenly exploded, and
a cloud of steam rushing out at the fracture, struck one of the men
who was near it, like a blast of lightning, and killed him in a
moment; when his companions endeavoured to take off his clothes, the
flesh came off with them from the bones.

_Account of the Wonderful Effects of two immense Burning-Glasses._

Mr. de Tschirnhausen constructed a burning-glass, between three and
four feet in diameter, and whose focus was rendered more powerful by a
second one. This glass melted tiles, slates, pumice-stone, &c., in a
moment; pitch, and all resins, were melted even under water; the ashes
of vegetables, wood, and other matters, were converted into glass;
indeed, it either melted, calcined, or dissipated into smoke, every
thing applied to its focus.

Mr. Parker, of Fleet-street, made a burning-glass, three feet in
diameter; it was formed of flint glass, and when on its frame, exposed
a surface of 2 feet 8-1/2 inches to the solar rays. It had a small
glass fitted to it, to converge the rays, and heighten the effect. The
experiments made by it were more powerful and accurate than those
performed by any other glass. The following is a brief epitome of its
astonishing power.

--------------------------------------+-------+-------+
Substances melted, with their weight; |Weight | Time |
and the Time in Seconds, whic