essays-1-第60节
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and a coating of plaster； which in this Figure is represented by the part marked by dots。 See page 351。
＇ IMAGE ＇
Fig。 14。 This shows how the breast of a Chimney may be brought down merely by a coating of plaster。 See page 351。
Footnotes for essay IV。
＇1＇ Eves and Sutton； bricklayers； Broad Sanctuary； Westminster； have alone altered above 90 Chimnies。The experiment was first made in London at Lord Palmerston's house in Hanover…square；then two Chimnies were altered in the house of Sir John Sinclair； Baronet； President of the Board of Agriculture； one in the room in which the Board meets； and the other in the Secretary's room； which last being much frequented by persons from all parts of Great Britain； it was hoped that circumstances would tend much to expedite the introduction of these improvements in various parts of the kingdom。 Several Chimnies were altered in the house of Sir Joseph Banks； Baronet； K。 B。 President of the Royal Society。 Afterwards a number were altered in Devonshire…house；in the house of Earl Besborough； in Cavendish…square； and at his seat at Roehampton；at Holywell…house； near St。 Alban's； the seat of the Countess Dowager Spencer：at Melbourne…house；at Lady Templeton's in Portland…place； at Mrs Montagu's in Portman…square； at Lord Sudley's； in Dover…street：at the Marquis of Salisbury's seat at Hatfield； and at his house in town；at Lord Palmerston's seat at Broadlands； near Southampton； and at several gentlemen's houses in that neighbourhood；and a great many others； but it would be tiresome to enumerate them all； and even these are mentioned merely for the satisfaction of those who may wish to make inquiries respecting the success of the experiments。
＇2＇ Having been obliged to carry backward the Fire…place in the manner here described； in order to accommodate it to a Chimney whose walls in front were remarkably thin；I was surprised to find upon lighting the fire that it appeared to give out more heat into the room than any Fire…place I had ever constructed。 This effect was quite unexpected； but the cause of it was too obvious not to be immediately discovered。The flame rising from the fire broke against the part of the back which sloped forward over the fire； and this part of the back being soon very much heated； and in consequence of its being very hot； （and when the fire burnt bright it was frequently quite red hot；） it threw off into the room a great deal of radiant heat。It is not possible that this oblique surface （the slope of the back of the Fire…place） could have been heated red…hot MERELY by the radiant heat projected by the burning fuel； for other parts of the Fire…place nearer the fire； and better situated for receiving radiant heat； were never found to be so much heated；and hence it appears that the combined heat in the current of smoke and hot vapour which rises from an open fire MAY BE； at least IN PART； stopped in its passage up the Chimney； changing into radiant heat； and afterwards thrown into the room。This opens up a new and very interesting field for experiment； and bids fair to lead to important improvements in the construction of Fire…places。I have of late been much engaged in these investigations； and am now actually employed daily in making a variety of experiments with grates and Fire…places； upon different constructions； in the room I inhabit in the Royal Hotel in Pall Mall；and Mr。 Hopkins of Greek…street Soho； Ironmonger to his Majesty； and Mrs。 Hempel； at her Pottery at Chelsea； are both at work in their different lines of business； under my direction； in the construction of Fire…places upon a principle entirely new； and which； I flatter myself； will be found to be not only elegant and convenient； but very economical。But as I mean soon to publish a particular account of these Fire…places；with drawings and ample directions for constructing them； I shall not enlarge farther on the subject in this place。It may however not be amiss just to mention here； that these new…invented Fire…places not being fixed to the walls of the Chimney； but merely set down upon the hearth； may be used in any open Chimney： and that Chimnies altered or constructed on the principles here recommended are particularly well adapted for receiving them。
The Public in general； and more particularly those Tradesmen and Manufacturers whom it may concern； are requested to observe； that as the Author does not intent to take out himself； or to suffer others to take out； any patent for any invention of his which may be of public utility； all persons are at full liberty to imitate them； and vend them； for their own emolument； when and where； and in any way they may think proper； and those who may wish for any further information respecting any of those inventions or improvements will receive （gratis） all the information they can require by applying to the Author； who will take pleasure in giving them every assistance in his power。
＇3＇ Kindling balls composed of equal parts of coal；charcoal； and clay； the two former reduced to a fine powder； well mixed and kneaded together with the clay moistened with water； and then formed into balls of the size of hens eggs； and thoroughly dried； might be used with great advantage instead of wood for kindling fires。 These kindling balls may be made so inflammable as to take fire in an instant and with the smallest spark； by dipping them in a strong solution of nitre and then drying them again； and they would neither be expensive nor liable to be spoiled by long keeping。 Perhaps a quantity of pure charcoal reduced to a very fine powder and mixed with the solution of nitre in which they are dipped would render them still more inflammable。
I have often wondered that no attempts should have been made to improve the fires which are made in the open Chimnies of elegant apartments； by preparing the fuel； for nothing surely was ever more dirty； inelegant； and disgusting than a common coal fire。
Fire balls of the size of goose eggs； composed of coal and charcoal in powder； mixed up with a due proportion of wet clay； and well dried； would make a much more cleanly； and in all respects a pleasanter fire than can be made with crude coals； and I believe would not be more expensive fuel。 In Flanders and in several parts of Germany； and particular in the Dutchies of Juliers and Bergen； where coals are used as fuel； the coals are always prepared before they are used； by pounding them to a powder； and mixing them up with an equal weight of clay； and sufficient quantity of water to form the whole into a mass which is kneaded together and formed into cakes； which cakes are afterwards well dried and kept in a dry place for use。 And it has been found by long experience that the expense attending this preparation is amply repaid by the improvement of the fuel。 The coals； thus mixed with the clay； not only burn longer； but give much more heat than when they are burnt in their crude state。
It will doubtless appear extraordinary to those who have not considered the subject with some attention； that the quantity of heat produced in the combustion of any quantity of coals should be increased by mixing the coals with clay； which is certainly an incombustible body；but the phenomenon may； I think； be explained in a satisfactory manner。
The heat generated in the combustion of any small particle of coal existing under two distinct forms； namely； in that which is COMBINED with the flame and smoke which rise from the fire； and which if means are not found to stop it； goes off immediately by the Chimney and is lost；and the RADIANT HEAT which is sent off from the fire； in all directions in right lines：I think it reasonable to conclude； that the particles of clay which are surrounded on all sides by the flame arrest a part at least of the combined heat； and prevent its escape； and this combined heat； so arrested； heating the clay red hot； is retained in it； and being changed by this operation to radiant heat； is afterwards emitted； and may be directed； and employed to useful purposes。
In composing fire balls； I think it probable that a certain proportion of chaffof straw cut very fine； or even saw dust； might be employed with great advantage。 I wish those who have leisure would turn their thoughts to this subject； for I am persuaded that very important improvements would result from a thorough investigation of it。
CONTENTS of ESSAY V。
A SHORT ACCOUNT of SEVERAL PUBLIC INSTITUTIONS Lately formed in Bavaria。 together with the APPENDIX to the FIRST VOLUME。
Account I A Short Account of the military academy at munich
Account II An account of the means used to improve the bread of horses； and horned cattle； in Bavaria and the Palatinate。
Account III An account of the measures adopted for putting an end to usury at Munich。
Account IV An account of a scheme for employing the soldiery in Bavaria in repairing the highways and public roads。
APPENDIX
No。 I Address and petition to all inhabitants and citizens of Munich； in the name of the real poor and distressed。
No。 II Subscription lists distributed among the inhabitants of Munich； in the month of January 1790； when the establishment for the relief of the poor in that city was formed。
No。 III An accoun
