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 learning, and in particular to the science of the Magi or Wise Men of Persia, from whom it was called magic. Natural magic is no more than the application of natural active causes to passive things or subjects, to produce effects apparently supernatural.

     Supernatural, beyond the powers of nature; miraculous.

Of what is Gunpowder composed?

Of saltpetre,[10] sulphur, and charcoal, mixed together and powdered; its explosive force when fired, is owing to the instantaneous and abundant liberation of gaseous matter by the intense heat resulting from the action of the combustibles upon the saltpetre.  It is not known by whom it was first applied to the purposes of war, but it is certain that it was used early in the fourteenth century.  Cannons were used at the battle of Cressy, in 1346; small guns, or muskets, were introduced into the Spanish army in 1521.