Admiral Pim pointed out that a red light would show four miles, while a green light was only visible for two miles and a half, so that, if a green light were seen, it indicated that the two vessels were within two miles and a half of each other.
Sir James Douglass said there was undoubtedly a weakness in regard to these lights; and he held that in the manufacture of lights effect should be given to the difference that existed in the various lights, so that, by making the green light more powerful, it could penetrate as far as the red, and in the same way making the red and green lights proportionately more powerful, so that they would penetrate as far as the white light.
Sir James Douglass said he had seen a parabolic reflector for sound tried, but, unfortunately, the reflector so intensified and focused all the sounds about the vessel and the noise of the sea that the operator could hear nothing but a chaos of sound.
The operation of carbonizing woolen rags for the purpose of obtaining pure wool, through the destruction of the vegetable substances contained in the raw material, maybe divided into two parts, viz., the immersion of the rags in acid, with subsequent washing and drying, and the carbonization properly so called. The first part is so well known, and is so simple in its details and apparatus, that it is useless to dwell upon it in this place. But the second requires more scientific arrangements than those that seem to be generally adopted, and, as carbonization is now tending to constitute a special industry, we think it is of interest to give here a typical plan for a plant of this kind. It will be remarked that this plan contains all the parts in duplicate. The object of this arrangement is to permit of a greater production, by rendering the operation continuous through half of the apparatus being in operation while the other half is being emptied and filled.
Figs. 4 and 5 give plans of the ground floor and first story, and Figs. 1, 2, and 3 give vertical sections. The second story is arranged like the first, and serves as a drier. As we have said, there is a double series of chambers for carbonization, drying, and work generally. These two series are arranged on each side of a central portion, which contains the heating and ventilating apparatus and a stone stairway giving access to the upper stories. The heating apparatus is a hot air stove provided with a system of piping. The rags to be carbonized or the wool to be dried are placed upon wire cloth frames.