chapter 16 (New York: Doubleday, Page & Co.).

"Shall we not," said Professor John Trowbridge, in an article published in the "New York Tribune," January 6, 1901, "in the next hundred years dispense with the limitations of wires and speak boldly through space, reaching some expectant human ear hundreds of miles away with the same ease that we now converse in a room? It is already possible to send messages by dots and dashes sixty to seventy miles without the use of wires. In the early days of the telephone this was the practical limit of that instrument, and we are all familiar with the immense extension which has taken place. Shall we not see a similar extension in the field of wireless telegraphy? Some late experiments which I have made lead me to be optimistic in regard to a possible great extension of the methods of wireless telegraphy.

"In the first place, I believe that these experiments prove that wireless telegraphy is not necessarily or merely accomplished through the air, but, on the contrary, that the earth plays the controlling part, and that the message flows, so to speak, through the earth or over its surface rather than through the air. The most striking experiment was as follows: The poles of a storage battery of twenty thousand cells were connected with the ground at the Jefferson Laboratory, and I was enabled to receive the message in a room three quarters of a mile from the laboratory without the use of masts or wires of any sort. The earth was the medium of communication, and it seems possible, by arranging the sending and receiving apparatus suitably in connection with the electrical capacity of the earth, that we may dispense with lofty masts and overcome in this way the curvature of the earth."

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Extensive experiments in wireless telegraphy are being conducted by the United States Weather Bureau, of which the following is a recent report: "Recognizing the advantage that would result to commerce and navigation by the establishment of wireless electrical communication between vessels at sea and exposed points on our lake and sea coasts, and also between islands along said coasts and the mainland, the Weather Bureau was directed to systematically investigate the various methods of electrical communication without wires. The progress made is eminently satisfactory. New appliances have been devised for the transmission of signals, and receivers have been constructed that probably are more delicate than any heretofore made. Messages already have been successfully transmitted and received over 50 miles of land, which presented a rough and irregular surface, conditions most unfavorable for the transmission of electro-magnetic waves. It is believed that the efficiency indicated by such transmission overland is sufficient to operate successfully over several hundred miles of water. The apparatus used is capable of further improvement. I hope the time is near at hand when the great number of craft employed in the coastwise commerce of the United States and over its great inland seas will be placed in instantaneous communication with the numerous stations of our Weather Bureau, which are located at all important ports. The matter is one of such great importance to our commerce that I have authorized extensive experimentation, which, from the success so far attending our efforts, will be vigorously prosecuted."

_United States, Annual Report of the Secretary of Agriculture, November 24, 1900, page 12._

On the 12th of March, 1901, the chief of the Weather Bureau, Professor Moore, gave to the Press the following statement as to experiments in progress along the Virginia and North Carolina coast: "The most efficient method of long distance transmission has been found to be from wire cylinders. The new coast stations are being equipped with cylinders of sixteen wires each and 140 feet in length. From these cylinders it is expected to cover a magnetic field of not less than five hundred miles. The stations now in operation are at Hatteras and at Roanoke Island, in Pamlico Sound, North Carolina. Workmen are beginning the construction of a station at Cape Henry, which will be the third station. When this is finished the two remote stations will be 127 miles apart."

MECHANICS: Steam turbines.

"The latest form of steam-engine recalls the first. The steam-turbines of De Laval and of Parsons turn on the same principle as the æolipile of Hero. That simple contrivance was a metallic globe mounted on axes, and furnished through one of its trunnions with steam from a boiler near by. As steam rushed out from two nozzles diametrically opposite to each other, and at tangents to the globe, there resulted from the relieved pressure a swift rotation which might have done useful work. … Before the steam-turbine could be invented, metallurgists and mechanics had to become skilful enough to provide machinery which may with safety rotate 10,000 times in a minute; Watt had to invent the separate condenser; means had to be devised for the thorough expansion of high-pressure steam; and the crude device of Hero had to be supplanted by wheels suggested by the water-turbine.

"The feature which gives the Parsons steam-turbine its distinction is the ingenious method by which its steam is used expansively. In a piston-engine the cylinder is filled to one-twelfth or one-fifteenth of its capacity with high-pressure steam, when communication with the boiler is cut off; during the remainder of its stroke the piston is urged solely by the steam's elasticity. In the Parsons turbine, by arranging what is practically a series of wheels on the same shaft, the steam passes from one wheel to the next, and at each wheel parts with only a fraction of its pressure and velocity. …

"The 'Turbinia,' a torpedo-boat of 44½ tons displacement, 100 feet in length, and 9 feet in beam, driven by this turbine, has consumed but 14½ pounds of steam an hour per indicated horse-power. The 'Viper,' a torpedo-boat destroyer of 325 tons, and provided with a turbine capable of developing as much as 12,000 horse-power, ran at the rate of 37 knots in a rough sea during her trial trip in November, 1899."

_G. Iles, Flame, Electricity and the Camera,