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

  • Michael Faraday
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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    room at any of the apertures; it all goes up, and out at the top; and if I were to hold a jar over the top I could show you in a moment the moisture there present. I will blow this out and make the smoke of the light enter into this place. If I put it there (varying the position) I expect you will see it all go up the chimney, and all go out of the top. There it is. You see there is none coming out at the lower apertures, the ventilation is perfect, all that is in the inside must go up, and it all passes up to the top, none gets out here or there. You will say, “ What is the amount of this ?” Look at the effects. I can by this kind of chimney carry up all the water out of the lantern of a light-house; it does not deposit itself and condense on the panes of glass of the lantern, as it used to do, but it goes out above. The use of that is this. When a lantern is put up in a light- house, which is always liable to gusts, the wind about the mouth or chimney will catch the mouth of the cowl, or the mouth out of which all the smoke is passing, and will not affect the light, showing, that although its mouth be surrounded by currents of air, it would not affect this. I might even put up a blowing apparatus there and it would not descend to the lamp ; it would not affect the light; it finds escape at this place. I find if I stop this place the light is not affected; and I may make a great many variations, and I dare say we shall make all these variations, and yet the lamp goes on burning uniformly and steadily. Now then, the first and most important thing in a light-house is, that the light should never vary; the light, above all things, must have the nursing care of those who are bound to attend to it, because on that the safety of the mariner depends. All other inconveniences must be borne with if necessary; but the light must go on burning steadily. I will show you by an experiment the necessity of keeping the thing clear and dry. What you see here on a small scale will be found equally prominent in a large one. First of all, let me show you an experiment. I will make a little light-house. Now, here is a glass jar, there is a chimney, (a small glass tube passed through the upper part,) here are some pieces of candle. I am going to make a little room, and then to put a chimney over a piece of candle if I can adjust it properly. I want the jar to be quite clear, and my glass is quite clear at present.
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