Oscillation, a swinging backward and forward.
Gravity, the tendency of a body toward the centre of the earth.
Registering, recording.
CHARCOAL BURNING.
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?