Lectures on electricity / by James Ferguson, F.R.S.

  • James Ferguson
Date:
1825
Catalogue details

Licence: Public Domain Mark

Credit: Lectures on electricity / by James Ferguson, F.R.S. Source: Wellcome Collection.

    66/112 (page 60)
    lake of! the ball G, that the sharp end of the wire within it may point toward the ball F. Then charge the jar., and you will be hardly able to make it discharge itself, nor will the feathers H expand any thing like what they did before. For the sharp point draws off the electric fire gradually from F; and, in a darkened room, it will be seen like a quiescent durable spark on the point of the wire. Which shews, that if a thuder- doud be over a house, where there is a complete metal conductor, the point will gradually draw down the lights ning from the cloud, and so prevent its accumulating therein, sufficient in quantity to break. The glass tube C D insulates the wire DEio Fy and prevents the electric fire, ‘discharged from the jar, from running down to the table in the direction EI) G; so that it can take no other course than what is shewn in the experiment.30 SECTION VI Medical Electricity 67. A girl, about seven years of age, belonging to the Foundling-hospital, was seized with a rigidity of all the muscles of her body, so as to be felt more like those of a dead corpse than of a living person ; her jaws were quite locked up, and she was very much emaciated. After having continued in this dreadful condition for a month, and all the usual medicines had failed, I)r. Watson ordered her to be electrified, which was begun about the middle of November, 1762; and continued, by intervals, till the end of January following, when every muscle in her body was perfectly flexible tso/e 30. An ingenious modification of this apparatus is sometimes em- ployed called the powder-house. It is so contrived, that when the electric discharge occurs, a quantity of gunpowder is ignited, and the explosion shews the disastious effects which would arise from the passage of the electric fluid through a magazine or powder-room.