Louis Laurent Simonin

“ When water rises in the shape of vapor, what is it that causes it to ascend? The heat of the sun. If it comes down as rain, forming torrents and brooks which feed our mill-races and drive our mills, what is it that turns the wheel? The sun, for it was the sun that in the first place raised the water. When the wind blows upon the sails of a windmill, or on the sails of a ship, what is it that drives the mill or propels the ship? ”

“ Then, having demonstrated that upon one square mile, using only one-half of the surface and devoting the remainder to buildings, roads, etc., we can drive 64,800 steam-engines, each of a hundred horse-power, simply by the heat radiating from the sun, he adds these remarkable words: "Archimedes, having completed his calculation of the force of a lever, said that he could move the earth; I affirm that the concentration of the heat radiated by the sun would produce a force capable of stopping the earth in its course." ”

“ In England they are beginning to calculate the time when the coal will give out, though coal-mines are, so to speak, of recent exploitation. A few thousands of years—drops in the ocean of time—will exhaust the coal-mines of Europe, unless, meanwhile, recourse is had to the aid of the sun. True, the sun's beams do not every day reach the surface of the earth; but, when the great magazine is opened which shall supply heat gratuitously without cost of transportation, the prudent engineer will know how to provide a reserve against cloudy days. ”

“ In the not distant future, in other countries, too, there will exist no other fuel than the sun, no other engines than those driven by solar heat. By that time no doubt the means of storing up this heat will have been discovered, for in our latitudes we shall have to make provision against cloudy days and seasons of rain, which unfortunately constitute the major part of the year.
It may appear to be a pleasant paradox to say that future generations, after the coal-mines have been exhausted, will have recourse to the sun for the heat and energy needed in manufacture and in domestic economy. ”

“ It cannot be objected that the conical reflector takes up too much room, for a common steam-engine occupies considerable space likewise with its long boilers and its high chimney; as for the motor, properly so called, and the contrivances for transmitting the power, they are the same in both cases.
The strongest winds, at least in our latitudes, have no action on the reflection of the solar heat, or upon the mirror itself, which is not shaken by them. This is an important point, for this is an apparatus which must always be exposed in the open air. ”

“ It is a pity that the inventor has never measured the real work performed by his engine, by means of a dynamometer.
The solar reflector, being first of all a furnace using fuel that costs nothing, is not only of use as a means of developing motive force, but can also be employed for a multitude of purposes—for instance, distilling water to make it fit for drinking, concentrating and crystallizing saline solutions, preparing alcohol, etc. Five litres of wine can be distilled in a quarter of an hour by passing the vapor from the apparatus into a still. ”

“ In regions where the wind-storms are more severe than they are here, the reflector might be staid and strengthened with iron ribs, so as to resist the most violent cyclones. It has been demonstrated that the bell-glass, even when highly heated by the direct radiation from the boiler, is in no danger of breaking, even when a cold rain falls upon it, and that it is even proof against hailstones; and now that a process has been. invented for tempering glass and making it almost unbreakable, we can without difficulty obtain bell-glasses strong enough for any emergency. ”

“ A steam-engine consists of two principal parts, the boiler and the engine proper, or motor. We suppose that with the boiler employed at Tours we can use the common motors; this is one of the advantages possessed by the solar apparatus, viz., that it does not require a special form of motor. At first the inventor employed for his demonstrations a double-acting engine, without either condensation or detention of steam, the cylinder of which had a capacity of one-third of a litre. This engine performed eighty strokes per minute, with a steady pressure of one atmosphere ”

“ In the mean time Ericsson was studying these same problems, without knowing anything about Mouchot's experiments. Starting from the facts collected by Herschel and Pouillet, Ericsson, in the first place, estimated the action of the sun upon a surface of nine square metres to be sufficient to vaporize eight litres of water; consequently it would be equal to one horse-power. From these premises he deduces striking consequences, as, for instance, that the solar heat falling on the roofs of Philadelphia alone would suffice to drive 5,000 steam-engines of twenty horse-power each. ”

“ Straw, sawdust, wool, feathers, confined air, are insulating substances which retain heat. We might surround with a double envelope of this kind the reservoir holding the sun-heated stones, and in this way we might have our store of solar heat, as now we have our store of ice. It is one problem whether we have to retain cold or to retain heat. ”

“ The roasting of meat, not requiring the same amount of heat as does the vaporization of an equal weight of water, can be performed in the open air, by the action of the solar reflector alone, the piece of beef, veal, or mutton being fixed upon a spit. In less than an hour we have in this way a very fine roast. The use of butter must be avoided, lest the chemical rays, by transforming the butter into butyric acid, should spoil the flavor of the meat. ”

“ Electricity, as a mechanical agent, is too costly; to produce electricity we have to consume copper, zinc, and acids. Now, one kilogramme of copper, zinc, or acid represents several kilogrammes of coal expended in procuring it. In reducing copper-ore according to the Welch method, sixteen kilogrammes of coal is consumed for each kilogramme of copper obtained. Hence it were reasoning in a vicious circle to suppose that electrical or electro-magnetic machines can usefully or economically take the place of steam-engines. ”

“ In those countries fuel is scarce, firewood is not abundant, and coal, which has to be imported from a distance, often from the mines of England, commands an exorbitant price. Already in southern countries sea-salt is obtained purely by the action of solar heat. ”

“ The sun, for wind is simply an atmospheric current produced by the heating of a stratum of air which, being dilated by the sun, tends to an equilibrium with strata of the same density, and hence rises, while a volume of cooler air takes its place. ”

“ As for directly storing up solar heat in good conductors or absorbents of heat which are then to be insulated—for instance, receiving the heat in porous black stones which are first exposed to the sun and afterward thrown into a great reservoir, just as snow is piled up in the ice-house—it involves no impossibility. ”

“ At the same time we would observe that a large proportion of the earth's surface is illumined by an ever-radiant sun. The solar engine's sphere of activity is as great as its dynamic power is considerable." Mr. Ericsson, who, besides genius, possesses wealth and a long experience, will doubtless some day take up again his studies upon the mechanical application of solar heat. Meanwhile, we must state what has been done in this direction by a Frenchman.
The traveler who visits the library of Tours sees in the court-yard in front a strange-looking apparatus. ”

“ To this end the alembic-head is connected, by an horizontal tube, with a worm, the latter descending in the form of a helix and dipping into a constant current of cold water, while the metallic vessel, containing two litres of wine, is inclosed in the glass cylinder and set in the focus of the reflector. The alcohol is collected after forty minutes of exposure to the sun. Inasmuch as the apparatus grows hot slowly and continuously, the alcohol is highly concentrated and possesses a very agreeable aroma. ”

“ We may say that it lends itself to every industrial use in which solar heat can be employed, especially in tropical countries where the absence of all kinds of fuel for industrial uses is severely felt. ”

“ Coal, in burning, gives up the solar heat which was stored up in it, and therefore it was that, on seeing a locomotive engine move, Stephenson said: "It is not the coal that drives this engine, it is the sun's heat stored up in the coal thousands of ages ago; locomotives are but the horses of the sun." We might make a like comparison with respect to wine and the alcohol it contains ”

“ It will not take thousands of years to exhaust the European coal-mines, but only hundreds, and not very many hundreds either. In England, as appears from recent calculations, the supply will have been consumed in two or three centuries at the farthest. Belgium, Germany, France, and the other countries of Europe, are no better off. The United States of America and the north of China have coal enough to last for one thousand years, and that is all. ”

“ Glass further possesses the property of resisting the exit of these same rays after they have been transformed into dark rays on the blackened surface of the boiler. None of these applications of physical laws present any novelty; people reduced them to practice instinctively, as it were, before men of science could assign the reasons. ”

“ Thus the engine offers all desirable safety, and may be provided with all the accessories of a steam-boiler.
The reflector, which is the main portion of the generator, has a diameter of 2.60 metres at its large, and one metre at its small base, and is eighty centimetres in height, giving four square metres of reflecting surface, or of insolation. The interior walls are lined with burnished silver, because that metal is the best reflector of the heat-rays: still brass with a light coating of silver would also serve the purpose. ”