your Electoral Highness the accompanying complete report and account of the results of the regulations recently introduced into the army of your Highness. Since, however, this is a matter of very great importance, and since the calculations therein included cannot have too strong corroboration, I humbly beseech your Electoral Highness, as well for your own satisfaction as for my vindication, to commit this report, together with accompanying documents, to the council of war, with instructions to investigate the same in the most thorough manner, and to present a suitable report on the Meanwhile I recommend myself most humbly and obediently to your Highness's grace and favour. same. Your Electoral Highness's Most humble, true, and most obedient COUNT RUMFORD. MUNICH, June 1, 1792. LETTER TO PROFESSOR PICTET OF GENEVA. SIR,I ought to have acknowledged sooner the receipt of your last friendly letter; but you will excuse me, I am sure, when you learn that I have been exclusively occupied in putting the last touches to my Essay on the Management of Fire and the Economy of Fuel which I have just sent to press. I thank you sincerely for your Essay on Fire. I have read it with much pleasure, and it has interested me peculiarly; and all the more because the route which you have followed in your researches is the same which I had adopted in treating this subject. You know, I suppose, that Dr. Hutton has written a paper to explain one of your experiments, that in which there was an apparent reflection of cold. I was much struck with this result, which was not only unexpected, but very extraordinary. Your explanation of the phenomena is ingenious and clear; but I cannot help desiring that a matter which is of so great consequence, and which leads to such important conclusions with reference to the theory of heat, should be examined from every point of view. I have a thermometer of a peculiar construction, which possesses an uncommon degree of sensibility. Each variation of a degree of Reaumur's scale causes an index, three inches long, to make four entire revolutions on a circular dial six inches in diameter. With this instrument I tried to vary your experiment by presenting to the thermometer, as it hung in my room stationary at about the 13th degree of Reaumur's scale, a large cake, or disk, of melting ice; but although I held it for a long time at a distance of half an inch from the bulb of the thermometer, to my great surprise the instrument gave no indication of being sensible of the presence of the ice; while on presenting my hand to the thermometer, at the same distance, the calorific rays which escaped set the index in motion almost immediately. The bulb of this thermometer is a spiral tube of very thin glass, filled with alcohol, and placed in a vertical position. Its diameter is about half an inch, and the tube makes five revolutions about the centre of the spiral. The diameter of the disk formed by this spiral is about five inches. The piece of ice which I presented to it was circular: it was about six inches in diameter and four inches thick. As the front of the disk of the thermometer is vertical, and the flat surface of the piece of ice was placed parallel to the disk, and directly in front of it, the descending current of air, which was cooled by contact with the ice, did not affect the thermometer at all; when, however, the ice was held immediately above the instrument, the index. moved backwards immediately, as might naturally have been expected. I was surprised that it did not affect it at all when placed side of it; and I should have been surprised even if I had never heard of your experiment, so strongly was I impressed with the idea of the effect which proximity ought to produce. If you have made any new researches on this curious subject, I shall be obliged to you if you will kindly inform me of the results, or will indicate to me other experiments which have been made on the same subject. As to the success of my efforts to perfect chimney fire-places, you will be able to get an idea of the economy of fuel effected when I inform you that, under the most favourable circumstances, I have been able to bring to boiling twenty pounds of ice-cold water, by the heat produced in the combustion of one pound of ordinary fir-wood, moderately dry; and that, by the heat produced in the combustion of thirty-three pounds of the same wood, I have been able to roast one hundred pounds of meat in a roaster of my invention in the Military Academy in Munich. This roaster has been used daily for seven years; and all those who have tasted the meat prepared in it agree that it is cooked with an uncommon degree of perfection. I send herewith a description, which has been recently forwarded to me from England, of the working of a kitchen established according to my principles in the Foundling Hospital in London. Mr. Bernard, secretary of the Hospital, writes to me that several other large hospitals are about to adopt these inventions. You can make such use of the paper as you think best, but I beg that you will finally return it to me. I send you also a trifle which you can keep. It is the result of some reflections on a subject of great importance, — a subject which, for the good of society, we could wish had been meditated upon more often than it has been, without passion, and with a philosophic camlness. The following results of my experiments and researches on heat will perhaps interest you. They are taken from my Essay on the Management of Fire and Economy of Fuel, which will soon appear, and from another Essay on Kitchen Fire-places, which will fol low it. Here follows an abstract of the essays mentioned. [This letter is translated from the French, as it appears in the "Bibliothèque Britannique (Science et Arts)," iv., pages 7-11.] PROPOSALS FOR FORMING BY SUBSCRIPTION, IN THE METROPOLIS OF THE BRITISH EMPIRE, A PUBLIC INSTITUTION FOR DIFFUSING THE KNOWLEDGE AND FACILITATING THE GENERAL INTRODUCTION OF USEFUL MECHANICAL INVENTIONS AND IMPROVEMENTS, AND FOR TEACHING, BY COURSES OF PHILOSOPHICAL LECTURES AND EXPERIMENTS, THE APPLICATION OF SCIENCE TO THE COMMON PURPOSES OF LIFE. to (Presented) by the MANAGERS of the INSTITUTION. INTRODUCTION. THE HE slowness with which improvements of all kinds make their way into common use, and especially such improvements as are the most calculated to be of general utility, is very remarkable, and forms a striking contrast to the extreme avidity with which those unmeaning changes are adopted which folly and caprice are continually bringing forth and sending into the world under the auspices of fashion. This evil has often been lamented; but few attempts have been made to investigate its causes, or to remove them. On the first view of the matter it appears very extraordinary indeed that any person should ever, in any instance, neglect to avail himself of an invention or contrivance within his power to obtain, that is evidently calculated to increase his comforts, or to facilitate his labour, or to increase the profits of it; but when we reflect on the subject with attention, and con |