An Essay on Electricity; Explaining the Principles of That Useful Science, and Describing the Instruments, Contrived Either to Illustrate the Theory,

This historic book may have numerous typos, missing text, images, or index. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. 1799. Not illustrated. Excerpt: ... CHAP. IX. OF ELECTRIFIED POINTS. Experiment Xcvii. Dissipation of electricity by a point. Present the pointed end of a wire towards a conductor which is positively electrified, a lucid globular point or star will appear on the point, and the electric fluid will be evidently conveyed away and dissipated from the conductor. Experiment Xcviii. Brush of electric light. Present a pointed wire towards a conductor that is electrified negatively; a lucid cone or brush will be seen diverging from the point, and the quantity of fire will be increased. Experiment Xcix. Star of electric light. The lucid star is seen on the collecting points of a positive conductor, while a diverging cone will appear on a point placed at the end of the conductor. To determine the direction of the electric fluid, has ever been an object of considerable importance to the electrician; as it would enable him to der eide on the truth of those theories, which have been invented to account for its phenomena, and greatly assist hitn in the progress of future discovery: to this end, much stress has been laid on the different appearance of the light which is perceived on the pointed ends of electrified conducting substances; as these have been supposed to elucidate fully this interesting question. The electric fluid appears as a diverging stream darting forwards into the air, from a point electrified positively. The luminous appearance on a point negatively electrified, is that of a small little globule or star. Now, as the air is known to resist the motion of the electric fluid, the rays of it would by this resistance be made to diverge; therefore, when this fluid is darting from a point into the air, it will assume the form of a lucid cone or brush. To this it has been objected, that these ...