e possess any certain account, was made in 1634 by Henry de Wycke, a
German artist; it was erected in a tower of the palace of Charles V.,
king of France. The pendulum was applied by Huygens, in 1656.

What is a Pendulum?

A weight so suspended from a fixed point that it may easily swing
backward and forward; its oscillations are always performed in equal
times, provided the length of the pendulum and the gravity remain the
same. It is said that the idea of employing the pendulum for the
measurement of time, was first conceived by Galileo, while a young
man, upon his observing attentively the regular oscillations of a lamp
suspended from the roof of a church in Pisa. It was not, however, till
the time of Huygens that a method was devised of continuing its
motions, and registering the number of its oscillations.

_Oscillation_, a swinging backward and forward.

_Gravity_, the tendency of a body toward the centre of the
earth.

_Registering_, recording.

[Illustration: CHARCOAL BURNING.]

[Illustration: GOLD MINERS WASHING ORE.]

To whom is the invention of Gunpowder ascribed?

Most authors suppose it was invented by Bartholdus Schwartz, a monk of
Goslar, a town of Brunswick, in Germany, about the year 1320; it
appears, however, that it was known much earlier in many parts of the
world, and that the famous Roger Bacon, who died in 1292, knew its
properties; but it is not certain that he was acquainted with its
application to fire-arms.

Who was Roger Bacon?

A learned Franciscan, born at Ilchester, England, in 1214. He studied
at Oxford, and afterwards became professor at that great University.
He was familiar with every branch of human knowledge, but was
especially distinguished for his extraordinary proficiency in the
natural sciences. To him we owe the invention of the telescope; that
of gunpowder is ascribed to him, as stated above, although we have no
evidence to show whether he discovered its ingredients himself, or
whether he derived the knowledge from some ancient manuscripts. Bacon
suffered some from the ignorance of the age in which he lived, many of
his experiments being looked upon as magic. He died at Oxford in the
year 1294.

What is understood by Magic?

Magic is a term used to signify an unlawful and wicked kind of
science, depending, as was pretended, on the assistance of superhuman
beings and of departed souls. The term was anciently applied to all
kinds of l