1. A number of small sheets are to be made separately. 2. These are to be couched, one by one, between blankets. 3. When a heap is formed it must be put under a strong press, to force out the water. 4. Then the blankets are to be taken away, one by one, and the sheets hung up to dry. 5. When dry they are to be again pressed, or if to be sized, they must be dipped into size made of warm water, in which glue and alum are dissolved. 6. They must then be pressed again to force out the superfluous size. 7. They must then be hung up a second time to dry, which, if the air happens to be damp, requires some days. 8. They must then be taken down, laid together, and again pressed. 9. They must be pasted together at their edges. 10. The whole must be glazed by labor, with a flint. In China, if they would make sheets, suppose of four and a half ells long and one and a half ells wide, they have two large vats, each five ells long and two ells wide, made of brick, lined with a plaster that holds water. In these the stuff is mixed ready to work. Between these vats is built a kiln or stove, with two inclining sides: each side something larger than the sheet of paper; they are covered with a fine stucco that takes a polish, and are so contrived as to be well heated by a small fire circulating in the walls. The mould is made with thin but deep sides, that it may be both light and stiff: it is suspended at each end with cords that pass over pullies fastened to the ceiling, their ends connected with a counterpoise nearly equal the weight of the mould. Two men, one at each end of the mould, lifting it out of the water by the help of the counterpoise, turn it and apply it with the stuff to the smooth surface of the stove, against which they press it, to force out great part of the water through the wires. The heat of the wall soon evaporates the rest, and a boy takes off the dried sheet by rolling it up. The side next the stove receives the even polish of the stucco, and is thereby better fitted to receive the impression of fine prints. If a degree of sizing is required, a decoction of rice is mixed with the stuff in the vat. Thus the great sheet is obtained, smooth and sized, and a number of the European operations saved. As the stove has two polished sides, and there are two vats, the same operation is at the same time performed by two other men at the other vat; and one fire serves. NEW AND CURIOUS THEORY OF LIGHT AND HEAT. Nov. 20, 1788. UNIVERSAL space, as far as we know of it, seems to be filled with a subtle fluid, whose motion, or vibration, is called light. This fluid may possibly be the same with that which, being attracted by, and entering into other more solid matter, dilates the substance by separating the constituent particles, and so rendering some solids fluid, and maintaining the fluidity of others; of which fluid, when our bodies are totally deprived, they are said to be frozen; when they have a proper quantity, they are in health, and fit to perform all their functions; it is then called natural heat: when too much, it is called fever; and when forced into the body in too great a quantity from without, it gives pain, by separating and destroying the flesh, and is then called burning, and the fluid so entering and acting is called fire. While organised bodies, animal or vegetable, are augmenting in growth, or are supplying their continual waste, is not this done by attracting and consolidating this fluid called fire, so as to form of it a part of their substance? And is it not a separation of the parts of such substance which, dissolving its solid state, sets that subtle fluid at liberty, when it again makes its appearance as fire? For the power of man relative to matter, seems limited to the separating or mixing the various kinds of it, or changing its form and appearance by different compositions of it; but does not extend to the making or creating new matter, or annihilating the old. Thus, if fire be an original element or kind of matter, its quantity is fixed and permanent in the universe. We cannot destroy any part of it, or make addition to it; we can only separate it from that which confines it, and so set it at liberty; as when we put wood in a situation to be burnt, or transfer it from one solid to another, as when we make lime by burning stone, a part of the fire dislodged in the fuel being left in the stone. May not this fluid, when at liberty, be capable of penetrating and entering into all bodies, organised or not, quitting easily in totality those not organised, and quitting easily in part those which are; the part assumed and fixed remaining till the body is dissolved? Is it not this fluid which keeps asunder the particles of air, permitting them to approach, or separating them more, in proportion as its quantity is diminished or augmented? Is it not the greater gravity of the particles of air, which forces the particles of this fluid to mount with the matters to which it is attached, as smoke or vapor? Does it not seem to have a greater affinity with water, since it will quit a solid to unite with that fluid, and go off with it in vapor, leaving the solid cold to the touch, and the degree measurable by the thermometer? The vapor rises attached to this fluid, but at a certain height they separate, and the vapor descends in rain, retaining but little of it, in snow or hail less. What becomes of that fluid? Does it rise above our atmosphere, and mix with the universal mass of the same kind? Or does a spherical stratum of it, denser, as less mixed with air, attracted by this globe, and repelled or pushed up only to a certain height from its surface, by the greater weight of air, remain there surrounding the globe, and proceeding with it round the sun? In such case, as there may be a continuity or communication of this fluid through the air quite down to the earth, is it not by the vibrations given to it by the sun, that light appears to us? And may it not be, that every one of the infinitely small vibrations, striking common matter with a certain force, enters its substance, is held there by attraction, and augmented by succeeding vibrations, ti the matter has received as much as their force can drive into it? Is it not thus, that the surface of this globe is continually heated by such repeated vibrations in the day, and cooled by the escape of the heat when those vibrations are discontinued in the night, or intercepted and reflected by clouds? Is it not thus, that fire is amassed and makes the greatest part of the substance of combustible bodies? Perhaps, when this globe was first formed, and its original particles took their place at certain distances from the centre, in proportion to their greater or less gravity, the fluid fire, attracted towards that centre, might in great part be obliged, as lightest, to take place above the rest, and thus form the sphere of fire above supposed, which would afterwards be continually diminishing by the VOL. III. 4 B substance it afforded to organised bodies, and the quantity restored to it again, by the burning or other separating of the parts of those bodies. Is not the natural heat of animals thus produced, by separating in digestion the parts of food, and setting their fire at liberty? Is it not this sphere of fire which kindles the wandering globes that sometimes pass through it in our course round the sun, have their surface kindled by it, and burst when their included air is greatly rarefied by the heat on their burning surfaces? May it not have been from such considerations that the ancient philosophers supposed a sphere of fire to exist above the air of our atmosphere? B. FRANKLIN. THE END. TO THE SELECT WRITINGS. ACCOUNT of a Toad found in the solid of a Stone Quarry, 449. Account of a species of Moth that lived 71 days after its head was cut off, 451. Advantages of Stoves that draw downwards, 512. Advice to a young Tradesman, 245. Advice to those who are about to undertake a Sea Voyage, 255. Air, an Essay on the free Use of, 374.-Moist Air not unhealthy, 422. Albany Papers, 1. America, the internal State of, 267. America, Information to those who would remove to, 259. America, Comparison of her Credit and that of Great Britain, 92. American Discontents before 1768, Causes of, 43. American Paper-Money, Remarks relative thereto, 33.-State of, 98. American Politics prior to the Independence of the United States, 1776, 1. Analogy between Magnetism and Electricity, 400, Animals, Effect of Lightning on the Eyes of, 459. Animal Food rendered tender by Electricity, 405. Answer to Mons. Dubourg's Queries respecting the Armonica, 359. Answers to Queries on the Art of Swimming, 407. Apologue, 309. Arabian Tale, 326. Armonica, a musical Instrument. Description of it, 354.-Answer to Mons. Dubourg's Ques- tions relative to the Armonica, 359. Articles of Belief and Acts of Religion, 187. Astronomical Conjectures, 370. Attempt to explain the Effects of Lightning on the Vane of the Steeple of a Church in Cre- Aurora Borealis, Suppositions and Conjectures relative thereto, 440. Bagatelles, 307.-To the Abbé Morellet, $49. Balloons, their probable importance, 464. 555. Beccaria, Letter to him on the Armonica, 354. Belief, Articles of, and Acts of Religion, 187. |