Lecture on light and ventilation : delivered at the Royal Institution, April 7, 1843 / by Professor Faraday.

  • Faraday, Michael, 1791-1867.
Date:
[1843]
Catalogue details

Licence: Public Domain Mark

Credit: Lecture on light and ventilation : delivered at the Royal Institution, April 7, 1843 / by Professor Faraday. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    from there for the purpose of this evening’s lecture. Here is a very beautiful model of a light-house erected recently at St. Catherine’s Tower in the Isle of Wight. Here is the tower, and there is the lantern in which the light is placed which is to give notice to the approaching or receding mariner of his whereabouts. Here are two models of what are called “the lanterns.” I will bring one upon the table for a moment, to show you more distinctly its general nature as a place needing ventilation. You see this is a model on a larger scale of the lantern of a light-house, very fairly and properly called a “lantern,” from its appearance and size; a small room raised to the top of a tower, fitted to resist the waves, as in the case of the Eddystone light-house, and the winds in all cases ; to hear all the beating about of those elements of nature, and yet withal to be walled only by glass, to be perfectly unchangeable; a place in which the man has to carry on his operations of watching the light and taking care of it, for sixteen hours in a winter’s night, and eight in a sum- mer’s night. Here is a model of one, which you perceive is a mode of producing and dispensing and sending forth the light. It is a large powerful lamp ; a strong light is put into the centre of the lantern, it is then surrounded by an arrangement of prisms, carved or cut in various forms or kinds across, with one place of lighting, the light radiating there, as it does here in this lamp, in that direction, rising up and down in a horizontal plane according to circumstances. All I need to trouble vou with here is, to think of a very powerful lamp. _ The painted parts, which you see. are coloured blue in the model, are glass. Now here is a lamp, which lamp, believe, varies in size ; it may be twelve or fourteen feet in diameter, perhaps from eight to ten high within. It is a very powerful lamp, which will burn from twelve to fourteen pints of oil in one night, or, it may be, in the case of separate lights, of which I have some there, there are various reflectors, each having its separate lamp, of an ordinary size, the same as this is. In that case, they vary from a small number up to twenty or thirty lamps, burning in one lantern. There is an arrangement, you see, of that kind of thing; there is a lantern containing the small reflectors, which they place in three planes, so that when the whole arrangement of parts revolves, it is <riving a recurring light, three times in one revolution,