62 



proper mixture of coal-gas and air. It became white hot, and con- 

 tinued 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 turpen- 

 tine, 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 con- 

 nexion of the facts detailed in this communication with those pre- 

 sented 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 lumi- 

 nous to guide him, while its relative brightness in different parts of 

 the mine will indicate the state of the air, and its fitness for respira- 

 tion ; for when the foul air forms two fifths of the volume of the 

 atmosphere, the ignition of the wire ceases. 



De la Structure des Vaisseaux Anglais, consider^ dans ses derniers 

 Perfectionnements. Par Charles Dupin, Correspondant de I'lnstitut 

 de France, fyc. Communicated by the Right Hon. Sir Joseph Banks, 

 Bart. G.C.B. P.R.S. Read December 19, 1816. [Phil. Trans. 

 1817, p. 86.] 



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 in- 

 troduced here in the art of ship-building ; and, in the present com- 

 munication, 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 de- 

 pend, 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 



