who had cared for him and for Nellie many times.

"Don't talk, Joe," he said. "Billy's all right-and so are you."

"Not my eyes, Doc," said Joe. He could feel the burn.

"Well, Joe," said the physician painfully, "your eyes are-are rather-are somewhat-"

But the wife broke into the stumbling sentences with a sob and Joe set his teeth. He did not need to be told, then. "Cooked!" he said.

Billy choked like a crying child. "Oh, Joe," he cried, his hoarse voice startling in the quiet, "why didn't you stay out and let me be? Did you know it was me, Joe?"

"Sure," said Emmons heavily. Then his courage came back again. "I saw you, Billy-I saw your face just before the steam come."

He turned to his wife and groped to draw her closer.

"Queer, ain't it," he added slowly, "that should be the last thing I'd ever see?"

enlargement and perfection of the machinery he has designed, as an outgrowth of his experiments, will go a long way toward the abolition of the engines that run only with a fire beneath the boilers and a smoke-cloud trailing away from towering chimneys. He is using the sun's rays instead,

aid of mirrors or lenses, on a boiler of some construction and with this boiler running an engine. Working along these lines, inventors, in consequence, found it absolutely necessary to keep a reflector pointed toward the sun, necessitating complicated clock movements. Mr. Shuman has entirely ignored this principle.

FRANK SHUMAN.

ether and connect with a nearby engine. The circuit is scientifically designated as a "closed" one and the ether in the pipes is converted into vapor in the hot-box, passes through the engine, developing the full power of the machinery, thence into the condenser and back again into the hot-box. Entire reliance is placed in the heat of the sun to convert the liquid into vapor and no other fuel is demanded to make this possible. In tropical climates water may be substituted for ether in the pipes. The economy of the idea is apparent.

In the unsuccessful experiments of other inventors there were a number of causes that contributed to the failure of their efforts, among them being: Enormous first cost of the installation per horse - power, running to about $1,000 per horse-power; impossibility of constructing large power units, ten horsepower being the maximum; fragility and great wear and tear of insulation; necessity of expert attendance; deterioration due to expansion and contraction; necessity for heavy construction to resist winds in the focusing reflectors, which were sometimes as large as thirty feet in diameter.

From the plenty of the sun's warmth he has taken such heat as that planet has been willing to impart to a big hot-box placed in the yard of his home in Tacony, which is a part of Philadelphia. This hot-box adheres to the principle of the common hot-bed used by farmers and florists. It is simply a big wooden frame, eighteen by sixty feet, sunk into the ground and covered with a double top of ordinary hothouse glass, with one inch of air-space between the layers. Below this coating of glass are coiled iron pipes, painted black, from which the inventor derives his power. These pipes, in the latitude of Philadelphia, are filled with

These objections are obviated in the Shuman engine which is based on the principle of utilizing the direct rays of the sun, without concentration, in his hotbox. This box acts to conserve the rays of the sun and, in Philadelphia, a temperature of 240 degrees, Fahrenheit, has been reached. In the tropics, Mr. Shuman estimates that 300 degrees Fahrenheit and higher will be easily obtained.

An outline of the detailed economies effected in the method of construction employed in the direct-acting solar engine includes the following:

Disadvantages encountered in the attempts to focus the sun's rays are not presented; first cost of construction is no more than that of a modern steam plant of the same power; engines can be made of any size and are capable of indefinite expansion; no difficulty is anticipated in the construction of a hot-box that will yield large horse-power.

Experiments have already demonstrated that the wear and tear in a solar plant is only about one-tenth of that of an ordinary steam-power plant. Any steam engineer can run it. The cost of attendance is likewise about one-tenth of the cost of a modern steam plant. There is no cost for fuel. Compared with this a water-power plant costs nothing for fuel but the first cost entailed in its erection is enormous as compared with the first cost of a solar plant. The one drawback to a solar-power plant, under the Shuman or any other system, is that even in tropical latitudes power is only available for one-third of the total time. At eight o'clock in the morning the power starts, reaches its maximum between eleven and three o'clock and then dies down at four o'clock. In engines which must run continuously this obstacle would necessitate the use of an accumulator.

Under average circumstances the announcement of a perfected invention that will eventually be put to such tests as this must meet would be taken with many grains of salt by a skeptical public and a still more skeptical scientific fraternity. But, by reason of its inventor's triumphs in other fields, it has received at once the attention it merits. He has been successful in converting to practical use many excellent but overcostly schemes and devices. He has received two Franklin Institute medals and has invented machines for making wire glass, perfected an installation system for concrete piling, together with other appliances which are controlled by companies having an aggregate capital of more than $20,000,000.

"Now I do not want you to take my theories too strictly," he cautioned in beginning a description of the solar engine,

its limitations and its wide possibilities. "I am not a theorist, but merely have the ideas that I intend to outline. They may be wrong, but of the working of my invention I am sure. The idea of generating solar power, as my engine has been doing for several months, occurred to me about two years ago when I was figuring out a method of saving the heat of compression in compressing air. One thought in connection with this was the reheating of the compressed air, and along these lines I conceived the idea of exposing the compressed air in pipes. under a double glass box, all parts of which are painted black. This would be gaining solar power. From that point it was easy to diverge into designing a true solar engine. I have applied for patents on between twenty and thirty methods of attaining these desired results and there is sufficient originality in the applications to afford me all necessary protection.

"There is nothing really new about solar power. Millions of dollars have been spent in the wrong direction and the experiments were actual failures. Thoughtful persons are likely to ask how I am able to secure temperatures as high as 240 degrees Fahrenheit in my Philadelphia hot-box when this temperature is not reached in the atmosphere which we breathe? Why, in other words, with this existent temperature, is not all humanity scorched out of existence? There is a great diversity of opinion as to the nature of the sun's rays, initial temperature and other attendant features. I am no more sure of the real action of the sun's rays than many scientists of greater eminence, but the most plausible theory of my hot-box is that the radiant heat of the sun striking the blackened metallic surfaces underneath two layers of glass is converted into ordinary heat which has longer wave lengths and will not pass off again to any great extent through sheets of glass with air-space between them, thus compelling their absorption by the liquid contained in the pipes. The radiant heat passes without obstruction through the two sheets of glass and the air space. The ordinary heat into which it is changed can only pass through very slowly. I am by no means able to retain all of this heat.

If

tropics it will be equally easy to obtain one hundred pounds per square inch steam pressures in water. Throughout the entire summer of the present year I have had only two days of bright sunshine; that is, two entire days. On all other days it has been rainy, cloudy or partly cloudy. Since I did not wish to interrupt my daily tests I felt compelled to introduce ether into my solar system because it boils at a much lower point than water. Its action is exactly the same as water in regard to generating mechanical power, although with ether I can run with decreased power on a nearly covered sun. This ether remains indefinitely in the pipes and none whatever is lost. Through an ingenious arrangement of the flash boiler very little ether is used.

"And now to answer the question that the public is most likely to ask. The solar rays do not heat the atmosphere to the same point as my hot-box because

my hot-box the radiant heat passes immediately through the glass on the blackened pipes. There is no circulation to allow the radiation of heat into space. The blackened surface converts the light into ordinary heat. Personally, it is my opinion that light and radiant heat are synonymous. From these collective ideas I have constructed an engine and with this machinery there has been pumped in excess of 100,000 barrels of water. It is efficient and beautiful in its work and thus far has never failed for a single moment. Nor has it demanded any repairs. Its simplicity is so pronounced that any boy can operate the mechanism."

The efficiency of this system has been so fully demonstrated that its inventor is now at work upon a fifty horse-power engine that will be erected next spring in the vicinity of Miami, Florida. The hot-box for this engine will be much larger than the present one, with which all of the tests have been made. The