Some of that class of individuals who envy all great men, and deny all great inventions, have ignorantly stated that Mr. Babbage’s invention is not new. The same persons, had it suited their purpose, would have maintained that the invention of spectacles was an anticipation of the telescope; but even this is more true than the allegation that the arithmetical machines of Pascal and others were the types of Mr. Babbage’s engine. The object of these machines was entirely different. Their highest functions were to perform the operations of common arithmetic. Mr. Babbage’s engine, it is true, can perform these operations also, and can extract the roots of numbers, and approximate to the roots of equations, and even to their impossible roots. But this is not its object. Its function, in contradistinction to that of all other contrivances for calculating, is to embody in machinery the method of differences, which has never before been done; and the effects which it is capable of producing, and the works which in the course of a few years we expect to see it execute, will place it at an infinite distance from all other efforts of mechanical genius.[33] [33] A popular account of this engine will be found in Mr. Babbage’s interesting volume _On the Economy of Manufactures_, lately published. LETTER XII. Wonders of chemistry--Origin, progress, and objects of alchemy--Art of breathing fire--Employed by Barchochebas, Eunus, &c.--Modern method--Art of walking upon burning coals and red-hot iron, and of plunging the hands in melted lead and boiling water--Singular property of boiling tar--Workmen plunge their hands in melted copper--Trial of ordeal by fire--Aldini’s incombustible dresses--Examples of their wonderful power in resisting flame--Power of breathing and enduring air of high temperatures--Experiments made by Sir Joseph Banks, Sir Charles Blagden, and Mr. Chantrey.