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Dictionary, will fix the rule and
facts in your memory.
NOTE. Mr. Brice discovered, from observations on the clouds, or their shadows moving on the surface of the earth, that the velocity of wind in a storm was nearly 63 miles in an hour, 21 miles in a fresh gale, and nearly 10 miles in a breeze.
Of the Steam-Engine.
FATHER. If you understand the principle of the forcing-pump, you will easily comprehend in what manner the steam engine, the most important of all hydrostatical machines, acts.
Charles. Why do you call it the most important of all machines? it is not a common one.
Steam-engines can be
used with advantage only in those cases where great power is required. They are adapted to the raising of
water from ponds and wells; to the draining of mines; and perhaps with
out their assistance we should not at this moment have the benefit of coalfires.
Emma. Then there cannot be two opinions entertained respecting their utility. I do not know what we should do without them in winter, or even in summer, since coal is the fuel chiefly used in dressing our food.
Father. Our ancestors had, a century ago, excavated all the mines of coal as deep as they could be worked without the assistance of these sort of engines. For when the miners have dug a certain depth below the surface of the earth the water pours in upon them from all sides; consequently they have no means of going on with their work without the as
sistance of a steam-engine, which is erected by the side of the pit, and, being kept constantly at work, will keep it dry enough for all practical purposes.
The steam-engine was inverted during the reign of Charles II, though it was not brought to a degree of perfection sufficient for the draining of mines till nearly half a century after that period.
Charles. To whom is the world indebted for the discovery?
Father. It is difficult, if not impossible, to ascertain who was the inventor. The marquis of Worces ter described the principle in a small work entitled," A Century of Inventions," which was published in the year 1663, and was reprinted a few years since in London.
Did the marquis con
struct one of these engines? Father. No; the invention seems to have been neglected for several years, when captain Thomas Savery, after a variety of experiments, brought it to some degree of perfection, by which he was able to raise water, in small quantities, to a moderate height.
Charles. Did he take the invention from the marquis of Worcester's book?
Father. Dr. Desaguliers, who, in the middle of the last century, entered at large into the discussion, maintains that captain Savery was wholly indebted to the marquis, and, to conceal the piracy, he charges him with having purchased all the books which contained the discovery, and burned