The Age of Invention | Page 6

public
purposes; yet he was able, at the early age of forty-two, to turn over his
printing office to one of his journeymen, and to retire from active
business, intending to devote himself thereafter to such public
employment as should come his way, to philosophical or scientific
studies, and to amusements.

From boyhood Franklin had been interested in natural phenomena. His
"Journal of a Voyage from London to Philadelphia", written at sea as
he returned from his first stay in London, shows unusual powers of
exact observation for a youth of twenty. Many of the questions he
propounded to the Junto had a scientific bearing. He made an original
and important invention in 1749, the "Pennsylvania fireplace," which,
under the name of the Franklin stove, is in common use to this day, and
which brought to the ill-made houses of the time increased comfort and
a great saving of fuel. But it brought Franklin no pecuniary reward, for
he never deigned to patent any of his inventions.
His active, inquiring mind played upon hundreds of questions in a
dozen different branches of science. He studied smoky chimneys; he
invented bifocal spectacles; he studied the effect of oil upon ruffled
water; he identified the "dry bellyache" as lead poisoning; he preached
ventilation in the days when windows were closed tight at night, and
upon the sick at all times; he investigated fertilizers in agriculture.
Many of his suggestions have since borne fruit, and his observations
show that he foresaw some of the great developments of the nineteenth
century.
His fame in science rests chiefly upon his discoveries in electricity. On
a visit to Boston in 1746 he saw some electrical experiments and at
once became deeply interested. Peter Collinson of London, a Fellow of
the Royal Society, who had made several gifts to the Philadelphia
Library, sent over some of the crude electrical apparatus of the day,
which Franklin used, as well as some contrivances he had purchased in
Boston. He says in a letter to Collinson: "For my own part, I never was
before engaged in any study that so engrossed my attention and my
time as this has lately done."
Franklin's letters to Collinson tell of his first experiments and
speculations as to the nature of electricity. Experiments made by a little
group of friends showed the effect of pointed bodies in drawing off
electricity. He decided that electricity was not the result of friction, but
that the mysterious force was diffused through most substances, and
that nature is always alert to restore its equilibrium. He developed the
theory of positive and negative electricity, or plus and minus
electrification. The same letter tells of some of the tricks which the
little group of experimenters were accustomed to play upon their

wondering neighbors. They set alcohol on fire, relighted candles just
blown out, produced mimic flashes of lightning, gave shocks on
touching or kissing, and caused an artificial spider to move
mysteriously.
Franklin carried on experiments with the Leyden jar, made an electrical
battery, killed a fowl and roasted it upon a spit turned by electricity,
sent a current through water and found it still able to ignite alcohol,
ignited gunpowder, and charged glasses of wine so that the drinkers
received shocks. More important, perhaps, he began to develop the
theory of the identity of lightning and electricity, and the possibility of
protecting buildings by iron rods. By means of an iron rod he brought
down electricity into his house, where he studied its effect upon bells
and concluded that clouds were generally negatively electrified. In June,
1752, he performed the famous experiment with the kite, drawing down
electricity from the clouds and charging a Leyden jar from the key at
the end of the string.
Franklin's letters to Collinson were read before the Royal Society but
were unnoticed. Collinson gathered them together, and they were
published in a pamphlet which attracted wide attention. Translated into
French, they created great excitement, and Franklin's conclusions were
generally accepted by the scientific men of Europe. The Royal Society,
tardily awakened, elected Franklin a member and in 1753 awarded him
the Copley medal with a complimentary address.*
* It may be useful to mention some of the scientific facts and
mechanical principles which were known to Europeans at this time.
More than one learned essay has been written to prove the mechanical
indebtedness of the modern world to the ancient, particularly to the
works of those mechanically minded Greeks: Archimedes, Aristotle,
Ctesibius, and Hero of Alexandria. The Greeks employed the lever, the
tackle, and the crane, the force-pump, and the suction-pump. They had
discovered that steam could be mechanically applied, though they
never made any practical use of steam. In common with other ancients
they knew the principle of the mariner's compass. The Egyptians had