He next goes on to describe the principle of his new plan of cooling:—'The method by which I propose to accomplish this consummation, so devoutly to be desired, is chiefly by taking advantage of the well-known property of air to rise in temperature on compression, and to fall on expansion. If air of any temperature, high or low, be compressed with a certain force, the temperature will rise above what it was before, in a degree proportioned to the compression. If the air be allowed immediately to escape from under the pressure, it will recover its original temperature, because the fall in heat, on air expanding from a certain pressure, is equal to the rise on its being compressed to the same; but if, while the air is in its compressed state, it be robbed of its acquired heat of compression, and then be allowed to escape, it will issue at a temperature as much below the original one, as it rose above it on compression. Thus the air, being at 90 degrees, will rise, if compressed to a certain quantity, to 120 degrees; if it be kept in this compressed and confined state until all the extra 30 degrees of heat have been conveyed away by radiation and conduction, and the air be then allowed to escape, it will be found, on issuing, to be of 60 degrees of temperature. If a cooler be formed by a pipe under water, and air be forced in under a given compression at one end, and be made to pass along to the other, it may thereby, if the cooler be sufficiently extensive, be robbed of all its heat of compression; and if the apparatus is so arranged, as it easily may be, that at every stroke of the pump forcing in air at one end of the pipe, an equivalent quantity of the cooled compressed air escape from under a loaded valve at the other, there will be an intermittent stream of cooled air produced thereby, of 60 degrees Fahrenheit, in an atmosphere of 90 degrees, which may be led away in a pipe to the room desired to be cooled.'
The only difficulty to be encountered consists in the erection and working of machinery. There can be little fear on this score. We have no doubt that any London engine-maker would hit off the whole scheme of an air-cooling machine in half an hour. What is wanted is a forcing-pump wrought by a one horse or two bullock-power. This being erected and wrought outside of a dwelling, the air will be forced into a convolution of pipe passing through a tank of water, like the worm of a still, and will issue by a check-valve at every stroke of the piston into the apartments to be cooled. Properly arranged, and with a suitable supply of water trickling through the tank, air at 90 degrees will be reduced to 60 degrees or thereabouts, which is the temperature of ordinary sitting-rooms in England. What, it may be asked, will be the expense of such an apparatus for cooling the air of a dwelling-house? We are informed that it will not be greater than that usually paid for heating with fires in this country; and if so, the expense cannot be considered a serious obstacle to the use of the apparatus. In the case of barracks for soldiers, hospitals, and other public establishments, the process will prove of such important service, that the cost, even if greater than it is likely to be, should present no obstacle to its application.
THE CHURCH OF THE CUP OF COLD WATER
One beautiful evening, in the year 1815, the parish priest of San Pietro, a village a few miles distant from Sevilla, returned much fatigued to his little cottage, where he found his aged housekeeper, the Señora Margarita, watching for him. Notwithstanding that one is well accustomed to the sight of poverty in Spain, it was impossible to help being struck by the utter destitution which appeared in the house of the good priest; the more so, as every imaginable contrivance had been resorted to, to hide the nakedness of the walls, and the shabbiness of the furniture. Margarita had prepared for her master's supper a rather small dish of olla-podriga, which consisted, to say the truth, of the remains of the dinner, seasoned and disguised with great skill, and with the addition of some sauce, and a name. As she placed the savoury dish upon the table, the priest said: 'We should thank God for this good supper, Margarita; this olla-podriga makes one's mouth water. My friend, you ought to be grateful for finding so good a supper at the house of your host!' At the word host, Margarita raised her eyes, and saw a stranger, who had followed her master. Her countenance changed, and she looked annoyed. She glanced indignantly first at the unknown, and then at the priest, who, looking down, said in a low voice, and with the timidity of a child: 'What is enough for two, is always enough for three; and surely you would not wish that I should allow a Christian to die of hunger? He has not tasted food for two days.'
'A Christian! He is more like a brigand!' and Margarita left the room murmuring loudly enough to be heard.
Meanwhile, the unwelcome guest had remained standing at the door. He was a man of great height, half-dressed in rags, and covered with mud; while his black hair, piercing eyes, and carbine, gave him an appearance which, though hardly prepossessing, was certainly interesting. 'Must I go?' said he.
The priest replied with an emphatic gesture: 'Those whom I bring under my roof are never driven forth, and are never unwelcome. Put down your carbine. Let us say grace, and go to table.'
'I never leave my carbine, for, as the Castilian proverb says, "Two friends are one." My carbine is my best friend; and I always keep it beside me. Although you allow me to come into your house, and do not oblige me to leave it until I wish to do so, there are others who would think nothing of hauling me out, and, perhaps, with my feet foremost. Come—to your good health, mine host, and let us to supper.'
The priest possessed an extremely good appetite, but the voracity of the stranger soon obliged him to give up, for, not contented with eating, or rather devouring, nearly the whole of the olla-podriga, the guest finished a large loaf of bread, without leaving a crumb. While he ate, he kept continually looking round with an expression of inquietude: he started at the slightest sound; and once, when a violent gust of wind made the door bang, he sprang to his feet, and seized his carbine, with an air which shewed that, if necessary, he would sell his life dearly. Discovering the cause of the alarm, he reseated himself at table, and finished his repast.
'Now,' said he, 'I have one thing more to ask. I have been wounded, and for eight days my wound has not been dressed. Give me a few old rags, and you shall be no longer burdened with my presence.'
'I am in no haste for you to go,' replied the priest, whose guest, notwithstanding his constant watchfulness, had conversed very entertainingly. 'I know something of surgery, and will dress your wound.'
So saying, he took from a cupboard a case containing everything necessary, and proceeded to do as he had said. The stranger had bled profusely, a ball having passed through his thigh; and to have travelled in this condition, and while suffering, too, from want of food, shewed a strength which seemed hardly human.
'You cannot possibly continue your journey to-day,' said the host. 'You must pass the night here. A little rest will get up your strength, diminish the inflammation of your wound, and'–
'I must go to-day, and immediately,' interrupted the stranger. 'There are some who wait for me,' he added with a sigh—'and there are some, too, who follow me.' And the momentary look of softness passed from his features between the clauses of the sentence, and gave place to an expression almost of ferocity. 'Now, is it finished? That is well. See, I can walk as firmly as though I had never been wounded. Give me some bread; pay yourself for your hospitality with this piece of gold, and adieu.'