Page:Proceedings of the Royal Society of London Vol 2.djvu/94

Rh proper mixture of coal-gas and air. It became white hot, and continued so till the mixture had lost its inflammability. Mixtures of other inflammable gases afforded similar phenomena, and likewise several inflammable vapours, as those of ether, alcohol, oil of turpentine, and naphtha. In these experiments, platinum wire is most successfully used; for it does not tarnish, and its radiating powers are slight. Palladium answers nearly as well; but the phenomena are not witnessed when wires of silver, copper, or iron are employed. It is suggested that many theoretical views will arise from the connexion of the facts detailed in this communication with those presented to the Society in the author's former paper on flame; and practical applications may also flow from the same source. By hanging some fine platinum wire, for instance, above the wick of his safety-lamp, the coal-miner will be lighted in mixtures containing such excess of fire-damp as to be no longer explosive; and where the flame is extinguished, the metal will become sufficiently luminous to guide him, while its relative brightness in different parts of the mine will indicate the state of the air, and its fitness for respiration; for when the foul air forms two fifths of the volume of the atmosphere, the ignition of the wire ceases.

Being engaged in collecting materials for a work entitled "A Picture of Naval Architecture in the 18th and 19th Centuries," the author was induced to visit this country, with a view to become acquainted with the various innovations and improvements lately introduced here in the art of ship-building; and, in the present communication, offers some remarks upon the plans proposed by Mr. Seppings, an account of which has formerly been before the Royal Society, and is printed in their Transactions for 1814.

After giving an outline of the fundamental principles upon which Mr. Seppings's improvements in naval architecture principally depend, and dwelling especially upon the diagonal pieces of timber which he employs to strengthen the usual rectangular frame-work, the author proceeds to state that similar contrivances were long ago suggested and even practised by the French ship-builders, in order to give strength to the general fabric of their vessels. Instead of making the ceiling parallel to the exterior planks, they arranged it in the oblique direction of the diagonals of the parallelograms formed by the timber and the ceiling, in the whole of that part of the ship's sides between the orlop and limber-strake next the kelson. They then covered this ceiling with riders, as usual, and placed cross-pieces between them in the direction of the second diameter of the parallelogram. This system, however, was abandoned in the French