An epitome of electricity & galvanism — John Shaqi
An epitome of electricity & galvanismGreen, Jacob
History
An epitome of electricity & galvanism
Green, Jacob
Electricity -- Early works to 1850
In the structure of an electrical kite, the circumstances to be
principally attended to are those near, and on the ground. Silk being a
non-conductor, the end of the string which is held in the hand is to be
of that substance—a silk handkerchief tied to the hempen twine of the
kite will answer very well. An iron key is to be tied on the hempen
string, an inch or two above its junction with the silk, and from this
key, when the kite is electrified, the sparks are to be received into a
Leyden phial, to be used in the same manner as if it had been charged
from the electrical machine. As curiosity may prompt many to repeat the
experiments made with this kite, and as no experiments with atmospheric
electricity can be made without some danger,[16] we shall give the
substance of Mr. Cavallo’s directions (the best we are acquainted with)
relative to the forming and using of this instrument.—He observes that
the whole power of the machine lies in the string: and that in other
respects a common school boy’s kite, will answer the purpose as well as
any other. The string is made by twisting two threads of twine with one
of brass wire or copper, such as is commonly used for trimmings. When a
kite constructed in this manner was raised, the string always gave signs
of electricity except once, when the weather was warm, and the wind so
weak that the kite could not be kept up for a few minutes; afterwards,
however, when the wind increased, he obtained as usual a considerable
quantity of electricity.
Concerning the management of this kite he gives the following
directions.—
In raising the kite when the weather is very cloudy and rainy, at which
time there is much danger of meeting a great quantity of electricity, I
usually hang upon the string a chain with one extremity touching the
ground; and sometimes I use another caution besides, which is, to stand
upon an insulated stool; in which situation, I think that if any
quantity of electricity, suddenly discharged by the clouds, strikes the
kite, it cannot much affect my person. Although I have raised my
electrical kite a hundred times without any caution whatever, I have
very seldom received a few exceedingly slight shocks in my arms. In time
of a thunder storm, if the kite has not been raised before, I would not
advise a person to attempt it while the stormy clouds are over head, the
danger at such time being very great, even when every caution is used.
At that time the electricity of the clouds may be observed by means of a
cork ball electrometer, placed in an open situation.
Public-domain text, read in full here on John Shaqi.
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