Concentration of Heat Effected by Means of Mirrors.
Within the past two weeks Dr. William Calver, a man of science who has been working for twenty odd years on the vastest material problem which has ever presented itself to mankind for solution, has been granted letters patent simultaneously in the United States, England, Germany, and France on an invention which contains within itself possibilities of a revolution as radical and of a reorganization of society as great as those which followed the first practical introduction of steam power. As a matter of fact the powers of imagination fail when one commences to contemplate the invention and its bearings on society with all the far-reaching consequences of its universal introduction. And yet men have been working for thousands of years at the problem which Dr. Calver claims to have completely solved. Scientists of every generation since the time when it was first propounded by Archimedes have studied and striven for its accomplishment.
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The correspondent of the Herald called on Dr. Calver at his home in Washington. The doctor is a man of something past middle age. Like many inventors, he seems thoroughly wrapped up in the work that he has accomplished and the work that he has in view.
"I believe, in fact, I know," said he in answer to a question, "that I have solved the problem of the direct conversion of the sun's rays into a heat which can be utilized on a far cheaper commercial basis than coal. I have also devised a method for the storage of this heat so that it can be used at any desired time and place. I feel that beyond a doubt I have settled forever the question of the actual commercial harnessing of the direct rays of the sun and of their conversion to the use of man.
"The process which I have invented is a distinct departure from anything which has ever before been attempted by men working in my line. My methods are the acme of simplicity. No complicated and costly machinery is used in a single portion of my invention. Once my machine is built, it will last practically indefinitely, and as long as the sun continues to give heat and light to man it will labor in his behalf.
"There is no limit to the intensity of the heat which I can generate. I can produce in one spot a heat vaster and more fierce than that on the face of the sun itself, and a greater heat than any now attainable through the combustion of known substances or through the agency of the electric are, which now furnishes the fiercest heat known to man.
"As to the cost of this heat for commercial purposes, I shall only say that I can furnish it at the mouth of the coal pit or on the edge of the forest for a tithe of the cost that it takes to dig and raise the coal and to cut down the timber. And the heat which I generate by this process is available for a thousand and one things for which fuel is absolutely unfit. With it I shall be able to smelt easily the hardest and most rebellious of the ores. With it I shall make a quality of glass which cannot exist at present. With it an innocuous gas can be made at a cost far less than it is now made from coal.
"I conceived the principles on which my invention is based in three days. I was a young man then. It is going on now thirty years that I have been laboring on it. You must come to my laboratory where I shall be glad to show you my apparatus and explain my methods."
The sight which met the reporter's gaze as he entered was both novel and interesting. In the centre of the inclosure stood a small round house, about twelve feet in diameter, roughly constructed and resembling an upright water tank.
This tank seemed to form the centre of a system of circular wooden tracks. And it was on these tracks that the unique features of the exhibit were located. These were nothing more nor less than a number of mirror frames. In the big frame, for example, to which Dr. Calver led the way, instead of a single solid mirror or reflector, which might naturally have been expected, there were a great number of small mirrors set in a series of rows one above another. These mirrors, which were only four by six inches in size, exposed to the sun a perfectly flat surface. The method of arrangement of the rows in the frame was slightly convex. It was found by a simple count that there were twenty-seven rows of thirty mirrors each in the entire frame, or eight hundred and ten mirrors in all.
"It will be understood," said Dr. Calver by way of explanation, "that the great question which confronted any one working in my field was that of arranging the reflectors of the sun's rays so that any number of them could be concentrated on the same point at the same time and kept there throughout the entire day. Working on this idea I have constructed the form of reflector which you see before you. To this I have given the name of 'pan-helio-motor,' Greek, which translated means 'universal sun-power.'
"This motor consists of the simplest arrangement possible. Each of the small, flat mirriors is attached to a simple gearing device by which it can be moved at pleasure. Each and all of these surfaces, four by six inches in size, can be concentrated on a very small surface at any desired distance. In practice they are concentrated on the reservoir in the centre of the yard. Each glass reflects from twelve to fifteen degrees of heat from the sun."
"How about the point of concentration when the sun moves around?" was asked.
"That is simple enough," said Dr. Calver. "The frame moves, too. It is geared and adjusted in such a simple manner as to be moved along the circular track by even the most ignorant of attendants."
"But how about the cloudy and rainy days?" questioned the writer.
"Simple enough; we can keep ice in hot weather; after exactly the same principle we can store and keep heat in cold weather for use by day and by night, in sunshine and in storm. Two well-known examples will suffice to explain the principle of our heat reservoir. For instance, the heat of the sun's rays goes through the closed glass of a hot-bed and raises the temperature within. Heat goes through glass, but it does not come back. It is a universally known fact that a brick or a bag of hot water retains imparted heat for a considerable length of time.
"What more simple, then, than to throw the concentrated rays from our mirrors through two thicknesses of glass and collect their heat in a reservoir of clay and stone on the inside. This is what has been done in the present instance, and in practical work on an extended scale this same principle will be applied, only to a much greater extent and on a much larger scale than in the small experimental reservoir here.
"At the same time it may be stated as a matter of interest that I have kept three hundred or four hundred degrees of heat—a much higher temperature than is needed to make steam—in this small reservoir for a week at a time.
"From the sixteen hundred mirrors in the laboratory here, which can all be concentrated on a single point, I have generated on the coldest days sufficient heat to solder copper and Russian iron. I have burned a brick half way through in half an hour. I have concentrated the combined heat from the mirrors on an ordinary unburned brick and have burned it so hard that it scratched steel."
Dr. Calver described a number of experiments which demonstrated the efficiency of his methods and the terrific amount of heat, nearly ten thousand degrees, which he can concentrate in a single spot. He then showed the party some of the brick which he had burned as well as the metals which he had melted and welded. Some of the simpler of these experiments he performed.
The rays from a couple of the smaller helio-motors were concentrated on a corner of the reservoir. Some one walked near and held a handkerchief for a moment at the point of concentration. A dazzlingly brilliant white light was reflected, causing every one around to close his eyes.
Dr. Calver reached down and picked a stick from the frozen soil. He mounted the reservoir, and holding the stick in one hand he focused by means of a small hand reflector the heat of the combined mirrors on a portion of the frozen wood. In a moment it cracked, smoked, and burst into a fierce flame.
Sixteen feet in front of a small helio-motor whose reflecting surface was but ten feet square he placed a tin boiler full of water. A few minutes after he had concentrated the mirrors on its surface the water was boiling merrily. "Why, that little trick could cook a dinner for a whole family in summer time," remarked a member of the party. "And the cost of cooking for the whole year would average about a cent a day," said the doctor.
When asked what he believed the effect of his invention would be on humanity, Dr. Calver said:—
"I had few better friends than the late Senator Leland Stanford, who knew my invention well and sympathized with my purposes and ends. Conversing with me he one day said of my helio-motor: 'If perfected, it will do more for humanity than all we have at present. The steam engine made a great revolution, and this will make another and a greater.' I have nothing to add to what my friend has said except that my invention is completed now," said Dr. Calver.
James M. Thomson.