and viewed very distinctly according to
the laws of refraction or reflection. Nothing certain is known
respecting the inventor of microscopes, or the exact time of their
invention, but that they were first used in Germany, about 1621.

_Minute_, small, diminutive.

_Refraction_, a change in the direction of a ray of light,
when it passes through transparent substances of different
densities.

_Reflection_, a turning back of a ray of light after
striking upon any surface.

What is the Steam Engine?

A machine that derives its moving power from the force of the steam
produced from boiling water, which is very great, especially when, as
in the steam engine, it is confined within a limited compass: this
useful machine is one of the most valuable presents that the arts of
life have received from the philosopher, and is of the greatest
importance in working mines; supplying cities with water; in working
metals; in many mechanical arts; and in navigation. By the aid of
steam, vessels are propelled with greater swiftness than those which
are wholly dependent on the winds and tides; and thus trade is
facilitated, and we are enabled to communicate with distant lands in a
much shorter space of time than was formerly consumed. On land,
railroads are constructed, on which steam carriages run with
astonishing rapidity, so that a journey which by coach and horses
formerly required two or more days, may now be performed in four or
five hours.

_Mechanical_, belonging to Mechanics.

To whom are we indebted for its invention?

Its invention is by most writers ascribed to the Marquis of Worcester,
an Englishman, about 1663; but it does not appear that the inventor
could ever interest the public in favor of this, or his other
discoveries. The steam engine of Captain Savery, also an Englishman,
is the first of which any definite description has been preserved. It
was invented in 1698. Since that period it has been successively
improved by various persons, but it is to Mr. Watt and Mr. Boulton, of
England, that it is indebted for much of its present state of
perfection.

By whom was the Steam Engine first applied to the purposes of
Navigation?

By John Fitch, of Pennsylvania. From papers in the historical
collections of Pennsylvania, it appears that the first successful
experiments were made at Philadelphia, in 1785, three years before the
attempts at Falkirk, and on the Clyde, in Scotl