[ John Percy, metallurgist. ] Autograph Letter Signed to 'Captain Donnelly', regarding 'warm work' at the House of Commons, and the preparation of the third volume of his 'Treatise on Metallurgy'.

1p., 12mo. In good condition, lightly aged, tipped-in onto part of a page from an album. He begins by stating that he is returning a 'paper altered and corrected'. He goes on: 'We have had some warm work at the H[ouse]: of Commons of late'. (Percy had been appointed Superintendent of Ventilation of the Houses of Parliament in 1865. Percy is 'working very hard at my 3d volume, a large portion of which is in type'. (The third volume of Percy's 'Treatise on Metallurgy', titled 'On lead', would appear in 1870.) The tome will be 'copiously illustrated and will contain the result of much work not previously published.' Postscript: 'I see Playfair is here'.