Central improvements. In his device a seventy-pound bull-head rail is used. The upper part of the rail is covered first by a porcelain insulating casing, which is in turn inclosed in a heavy wooden shield whose cross section looks like a diminutive gambrel roof. The only part of the rail not covered is that beneath this insulating hood, which it is almost impossible to come in contact with without such deliberate action as is exerted by the springs that press the contact shoe of the motors against it. The rail is supported by cast-iron pedestals shaped like the neck of a goose, so as to avoid interference with the movement of the contact shoe. As a result of this arrangement, the rail is not only protected from rain and snow, but from the stumbling bodies of men who might inadvertently or through carelessness fall upon it. No precaution, however, is adequate to guard against the caprices of human curiosity. With this thought in mind, I asked the engineer who was guiding me through the yard whether any freak accident had occurred since the new third rail had been installed. out of that cheap at the cost of some thousands of dollars." Then he told me that the men whom the road employed on the excavation and construction work were newly imported Italians. For many months they had lived in intimate daily relations with the steam-engines that went to and fro in the yards. When the first section of the new equipment was completed, and the trains began to move through the yards without the assistance either of steam-engines or of any other apparent motive power, the Italians were puzzled. "You might have seen them," said my guide, "almost any day gathering in groups and talking confidentially to one another about the mystery that had fallen among them. After a time the most adventuresome member of the gang decided that he had located the deviltry in the third rail, and he determined to make an investigation. He was walking across the yard one afternoon, a crowbar in one hand and a spade in the other. When no one was looking, he thrust his spade under the hood of the third rail. Immediately there was a flash of fire. He howled and ran, drop "Only one," he replied, "and we got ping his crowbar as he went. The crowbar somehow got caught between the third rail and the track. A short circuit was established, and the electric fire spread across the entire electrified section of the yards. Submerged transmission cables were destroyed, fuses were everywhere burned out, and property worth some thousands of dollars was ruined. The meddler ran howling across the yards as if the very devil were indeed after him, and jumped over the edge of one of our deepest excavations. He was taken to the hospital with a broken leg. I hear that he has recovered since, but we have seen nothing further of him. As for the remainder of the gang, they were so thoroughly demoralized with fright that it took days to get them back to steady work. It was a costly accident, but it served a good purpose. There has been no loss of life or of property through triffing with the third rail since." ERECTING A SECTION OF THE TUNNEL LINING The electric locomotive looks as though two tenders had been detached from their engines and joined, back to back, by a box-like cabin. Both tenders are engines, and together are capable of developing 2,200 horse-power. In swiftness of acceleration and in ultimate speed the electric locomotive has surpassed the best type of steamengine as a drawer of moderately heavy passenger trains. It derives its power by shoecontact with the under side of the third rail, already described. Besides doing away with the smoke and gas generated by a steam-engine, it has the further advantage that, being a double-header, it is always in position to go forward, thus obviating the use of turn-tables, and making for economy both in yard space and in labor. It has been tested in all weathers and under all conditions that arise in practice, and has proved itself perfectly efficient. Only less important from the point of view of the transportation problem of New York than Sprague's invention is the invention of the English engineer Greathead, for it may be justly said that without the shield which he devised the great tunnels beneath the Hudson and East Rivers would have remained impossible. The story of the manner in which Greathead's inventive genius was brought to bear upon the traction problem of New York is an exceedingly romantic one. As early as 1879 a company of enterprising gentlemen concluded that tunnels must sooner or later supplant bridges as highways between Manhattan and the mainland. They decided that the best way to open the gates of New York was to burrow beneath the Hudson to the Jersey shore. With this object in view, they sank a brick shaft on the New Jersey side, and started to tunnel eastward. Their work workers, making their progress impossible. Undaunted, they decided to drive a temporary entrance or heading into the silt, from which to construct their tunnel tubes. This was accomplished by erecting, outside the air-lock, two rings formed of wrought-iron plates and angles, six feet four inches in diameter, four feet long, and bolted together. Then they ran a series of similar rings, each two feet six inches wide, and each succeeding one increasing about one foot six inches in diameter, until with the eleventh ring they reached the full diameter of the was watched with curiosity by all the world, for they were the first to attempt the construction of a great tunnel with the exclusive assistance of compressed air. When they had gone twenty-three feet below tide-level, they built an airlock into their brick shaft, from which they hoped the tunnel could be started. They decided to begin the break-up for the tunnel by opening the earth outward and timbering the roof of their excavation, while the sand or the rock or the silt of which it was composed was being removed and lifted to the surface. But the compressed air blew its way through the silt and permitted the water from the river above to filter down upon the projected tunnel. With the aid of compressed air, which held up the silt and water at the face of this improvised tunnel, they began their work of excavation and started the construction, within a thin iron casing, of a tubular wall of brick, the material of which their permanent tunnel was to be made. They had not gone far, however, when one of the rings of the improvised temporary tunnel, which led from the air-lock to the tube of brick, yielded to the pressure of the compressed air. The tunnel was flooded and wrenched out of shape by the inrushing water, and twenty men were drowned. The company attempted by many other fruitless experiments to |