Report of a Tour of Inspection of European Lighthouse Establishments, Made in 1873 |
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acoustic Argand burner atmosphere Augustin Fresnel beam buoys burner burning candles Captain carbon catadioptric catoptric Chance Brothers chimney coast colza colza-oil consumption Coquet Island cost diameter dioptric dioptric apparatus distance Doty Douglass eight Elder Brethren electric light engineer English experiments feet first-order fixed light flame flashes fog-signal four-wick France French Fresnel gallon gas-burner gas-light Haisborough heard Hève Honfleur horns hour Howth Howth Baily illuminating power inches intensity jets keepers lantern lens lenses light-house light-ships Longships lower luminous magneto-electric machines Maplin Sand ment miles mineral oil mineral-oil observed oil-lamp oil-light optical paraffine Phares placed Plate pounds prisms Professor Tyndall ratus red cut reflectors revolving rock sash-bars shown signal siren sound Souter Point South Foreland South Stack station steam tested thick tion tower triform Trinity House trumpet tube United vertical Villejuif watch-room weather whistle Wicklow Head wicks Wigham wind
Popular passages
Page 29 - As I stood upon the deck of the 'Irene' pondering this question, I became conscious of the exceeding power of the sun beating against my back and heating the objects near me. Beams of equal power were falling on the sea, and must have produced copious evaporation. That the...
Page 20 - shall mean the master wardens and assistants of the guild, fraternity, or brotherhood of the most glorious and undivided Trinity and of St. Clement in the parish of Deptford Strond in the county of Kent...
Page 32 - The instruments, hidden from view, were ou the summit of a cliff 235 feet above us, the sea was smooth and clear of ships, the atmosphere was without a cloud, and there was no object in sight which could possibly produce the observed effect. From the perfectly transparent air the echoes came, at first with a strength apparently but little less than that of the direct sound, and then dying gradually and continuously away.
Page 260 - The undersigned, envoy extraordinary and minister plenipotentiary of the United States of America, has the honor to acknowledge the receipt of...
Page 58 - Now it frequently occurs that a signal, which under ordinary circumstances would be audible at the distance of fifteen miles, cannot be heard from a vessel at the distance of a single mile. This is probably due to the reflection mentioned by Humboldt. The temperature of the air over the land where the fog-signal is located, being very different from that over the sea, the sound — in passing from the former to the latter, undergoes reflection at their surface of contact. The correctness of this...
Page 37 - II., a fixed disk and a rotating disk are employed, but radial slits are used instead of circular apertures. One disk is fixed vertically across the throat of a conical trumpet...
Page 28 - ... does not possess the molecular continuity of the crystal, but is a mere aggregate of minute grains not in perfect optical contact with each other. Where this is the case a portion of the heat is always reflected on entering and on quitting a grain ; hence when...
Page 28 - Thus, by the mixture of air and ice, two transparent substances, we produce a substance as impervious to light as a really opaque one. The same remark applies to foam, to clouds, to common salt, indeed to all transparent substances in powder. They are all impervious to light, not through the real absorption or extinction of the light, but through internal reflection. Humboldt, in his observations at the Falls of the Orinoco, is known to have applied these principles.
Page 32 - Edwards, who was good enough on this and some other days to act as my amanuensis, at 1 PM I was rowed to the shore, and landed at the base of the South Foreland Cliff. The body of air which had already shown such extraordinary power to intercept the sound, and which manifested this power still more impressively later in the day, was now in front of us.
Page 30 - We then learned that when the flag was hoisted the horn-sounds were heard, that they were succeeded after a little time by the whistle-sounds, and that both increased in intensity as the evening advanced. On our arrival, of course...