St. Nicholas/Volume 40/Number 8/With Men Who Do Things
WITH MEN WHO DO THINGS
BY A. RUSSELL BOND
Author of “The Scientific American Boy” and “Handyman’s Workshop and Laboratory”
Chapter VII
SPINNING A WEB ACROSS THE RIVER
“You mean the towers,” I ventured.
“Oh, no, they could n't begin to stand up against the pull of those cables. We just put in the towers to raise the bridge high enough above the river—something after the fashion of the clothes-poles with which a washerwoman props up her clothes-line. Why, you have no idea what a strong pull there is on the bridge cables. We have to build great masses of stonework, and imbed in the masonry enormous steel bars linked together like giant chains, to which the cables are fastened. The anchorages of this bridge are each as long as a city block (225 feet), and 175 feet wide, and when they are finished, they will be built up as high as an eight-story building.”
With this impressive introduction, Mr. Blanchard led the way up to the anchorage, and let us see for ourselves the huge chain of eye-bars. They were stringing the cables in separate strands, and each strand was fastened to a separate pair of eye-bars.
As Mr. Blanchard was anxious to inspect the work at the other end of the bridge, he did not stop to explain this just then, but started with us up one of the temporary foot-bridges that ran up, under each cable, to the nearer tower.
It was quite a climb, particularly as we neared the top, where the slant of the footwalk was very steep. The towers, reaching up to a height of 350 fect above the water, had looked very slender from a distance, and hardly strong enough to sustain the weight of a heavy double-deck bridge; but we found on closer inspection that they were made of massive steel, rising 322 feet above the masonry pier.
“They 're tremendously strong, are n’t they? I should think they would stand up under almost any load,” remarked Will.
“They ‘ll carry the load,” said Mr. Blanchard, “but we expect them to sway some, back and forth. the top may move one way or the other, as much as two feet from the upright position.”
“Why, how 's that?” I queried.
“When the summer sun beats upon the cables, they will grow so hot that it would be uncomfortable to put your hand on them, and you will find that they will have expanded considerably. On the other hand, when the bitter cold winds of winter chill them down below zero, they will contract appreciably. We expect the cables to be twenty or thirty inches shorter in winter than summer. The total change will be greater in the long span between the towers than in the shorter shore spans from the towers to the anchorages, and so the towers will have to bend to accommodate themselves to this variable pull. In the Brooklyn Bridge, the cables pass over cradles on rollers, so that they can travel back or forth with the cable to allow for these variations in the length of the spans, In this bridge, we are going to let the cables rest directly on the towers, and let the towers themselves bend back and forth, to allow for differences in length of the cable. I don’t suppose they will ever bend much more than six inches one way or the other, but we have allowed for a flexure of twenty-four inches.”
We followed Mr. Blanchard down one of the steep foot-bridges and up the opposite tower. It was quite a long walk, over a quarter of a mile in a straight line, and considerably more following the curve of the cables, as we had to, The foot-bridges were merely continuous platforms, about nine feet wide, and supported on temporary cables under the four main cables that were being strung. I kept strictly to the center line of that platform, and did n’t pay much attention to the boats that were plying back and forth beneath us. The foot-bridges were connected in pairs every five or ten feet, by means of beams, and at various intervals there were cross-walks connecting the south pair of bridges with the north pair. It made my flesh creep to see the workmen walk across the narrow beams between the platforms.
All the time, the wire carriers were traveling back and forth over our heads, just like spiders spinning their threads across the river. The carriers were merely large pulley-wheels connected to traveling-cables. The wire was looped over the pulley-wheel, and as the wheel traveled across, it would string two lengths of wire at once.
When we had reached the opposite side of the river, Mr, Blanchard explained the wire-string-ing process. The steel wire was about half the size of a lead-pencil, but it was strong enough to lift forty men. It was wound on enormous reels weighing four tons each, and with 80,000 feet of wire to the reel. When the cables were finished, they would be nearly two feet in diameter, 21¼ inches, to be exact. Each cable was made up of 9472 wires, strung in thirty-seven separate strands of 256 wires each. Altogether, in the four cables there would be 23,132 miles of wire, or enough to go nine tenths of the way around the earth.
The wire in a strand, he said, was looped around “shoes” at each end of the bridge, and ran in a continuous length, like a skein of silk. When the strand was completed, the ends were spliced together. When the strand was started, the wire was temporarily fastened at one end and passed around the shoe. Then it was slipped over the carrier, a signal was given, the cable started, and the carrier proceeded merrily on its way across the river. When it reached the top of the first tower, the lower reach of wire was gripped and hauled up until adjusted as to tension, so that the sag would correspond with a standard guide wire. Then it was clamped, and the signal was sent to the next tower, where it was similarly gripped and adjusted. This done, a signal was sent on to the anchorage, where the final adjustment took place. As soon as the carrier released this wire, it took back with it a pair of wires of another skein, which gave time for adjusting the upper reach of wire just strung. The wires were laid at one side of the position they were to occupy in the final cable, and when the strand was completed, it was moved out of the temporary rollers upon permanent shoes, The work of splicing the ends of the strand together usually took about five minutes. The shoes on which the strands were built up were horizontal. When a strand was completed, the shoes had to be drawn back by a hydraulic jack, turned on edge, and pulled back between a pair of steel eye-bars. Here they were made fast by a cross-pin. As the carriers strung two wires at a time, it took only six days to complete a strand. The wire was drawn through heavy oil and graphite, to prevent rusting while the cable was being made up.
We spent many hours on the bridge, examining the work, just how many I do not know; but it did not seem long before we heard several factory whistles, which warned us that it was five o’clock, and quitting time. We followed Mr. Blanchard down to the wash-room, and began to wash up. We were on the Brooklyn side, and as I was washing my hands, I looked over across the water to the tall bridge-tower on the New York side. A thin wisp of smoke was curling up from the very top of the structure.
“That tower looks just like a factory chimney,” I remarked to Mr. Blanchard.
“Eh, how ’s that?”
“Don’t you see the smoke coming out of the top of it? It seems to be getting thicker.”
Mr. Blanchard took one look at the tower, then rushed to the telephone and rang up the office on the other side; but could get no answer, He rattled the receiver hook wildly, growing more excited every moment. Finally, he threw the instrument down violently, and tore out of the room without a word to us. We did n’t stop to replace the receiver on the hook, but followed him as fast as we could up to the top of the Brooklyn tower, and then along the foot-bridge to the other side, The smoke was pouring in dense volumes from the tower now, and we could see the flames that were eating up the woodwork. It seemed like an endless run across that long foot-bridge. I had n't time to think of getting dizzy now, My eyes were on the blazing tower, that seemed miles away. Down below us a fire-boat was screaming, and the clang of fire apparatus showed us that the fire-department had responded promptly. I could see that quite a crowd of men had collected and were trying to put out the fire.
We were on the north foot-bridge, and just as we neared the burning tower, a gang of men rushed down the foot-bridge and across the small connecting bridge to the south foot-bridge. They had tools with them, and apparently their idea was to cut off enough of the timber to prevent the fire from creeping across the bridge to the Brooklyn side.
“Come back here, you,” yelled Mr, Blanchard, when he saw what they were up to. They were so intent on their work that they did n’t hear him, At any rate, they did n't heed, but started right in chopping off the planks. Mr. Blanchard did n’t stop for argument, but ran across the bridge and began hauling them back by main force. He was so excited he could scarcely speak, “What is the matter with you?” he cried; “don't you know the fire will burn through the cables and drop you, foot-bridge and all, into the river?”
It finally dawned on them what he was after, and they scampered back, Mr. Blanchard bringing up the rear. Just as he was half-way between the two footwalks, the cables gave way. and down crashed the south bridge. The connecting cross-walks gave our bridge a yank that sent us all sprawling. Will, who was near the edge,
“A SPOOL OF WIRE ON THE GEAR WINDS THE WIRE AROUND THY CABLE.” (SEE PAGE 740.)
almost rolled overboard, but one of the men grabbed him by the waist of his trousers just as he was teetering over the brink, and hauled him inboard. I did n’t see that incident because my
THE ANCHORAGE. EACH STRAND OF CABLE IS FASTENED TO ITS OWN ANCHOR CHAIN.
 THREE HUNDRED FEET ABOVE THE RIVER. |
 STRINGING THE LAST PAIR OP WIRES ON A CARRIER BEARING TIE STARS AND STRIPES. |
The fallen foot-bridge did not drop into the river, but was caught in the tangle of suspended cables, Some of the burning timbers dropped into the water, narrowly escaping a ferry-boat that was passing under at the time. There was nothing for us to do but to run on up to the tower and give what aid we could there, in fighting the fire. Things were in a pretty bad way. The cotton-waste and oil-soaked timbers, and the barrels of tar and paint and oil, made the very best of fuel, but to fight the fire there was only a single harrel of drinking-water, which had already been used to no avail. The fire-beat could n’t begin to reach us, and fire-engines about the
“ALL STRANDS WERE SQUEEZED TOGETHER TO FORM A CORE.” (SEE PAGE 740.)
“MR. BLANCHARD DIDN’T STOP FOR ARGUMENT, BUT RAN ACROSS THE BRIDGE.”
That retreat was an exciting one. The fire had spread to the northern side of the Lower, and as we ran down the stairway, blazing brands kept dropping on us. To add to our peril, there were several barrels of bolts at the top of the tower, and these were heated to redness in the fire, and, as the barrels and flooring burned away, they began to drop down upon us. I did n’t know at what moment a heavy bolt might strike me on the head and lay me out. A man in front of me had his clothing set afire by an incandescent bolt, which fell on the edge of his coat-pocket and hung there a moment. We were not half-way down the tower when there was a crash, and the north foot-bridge fell; but we were so busy dodg-ing firebrands and bolts that we did n’t even pause in our rush down the stairs.
That fire was one of the oddest the New York fire-department ever had to tackle. They could really do nothing but let the fire burn itself out at its own sweet will.
When we went around to see Mr. Blanchard a few days later, he explained to us just what damage had been done to the main cables. It was evident that the cables had been heated red hot during the fire, because they were badly burned and flaked. A number of wires would evidently have to be cut out and replaced with new sections. Some of the less seriously injured wires were cut out and sent to have their strength tested. These tests were very favorable, and showed that the cables were not half so badly damaged as it was feared that they might he.
Near the end of the summer, we visited the bridge again, so as to watch the cable-winding process after all the strands had been strung. First, several strands were squeezed together with crescent-jawed tongs, and fastened, at intervals, to form a core for the cable. Then the other strands were grouped about them and fastened temporarily, After this, the wire-winding machine was mounted on the cable. This was a large gear-wheel in two parts, bolted together about the cable. A traveler arranged to move along the cable carried a small electric motor that turned a pinion or small gear-wheel, fitting into the large gear, and in that way made the gear rotate around the cable. A spool of wire on the gear was carried around with it, winding the wire around the cable. A brake on the spool kept the wire under a constant tension. After the wire was wound, a steel sheathing made in half-sections was bolted about the cable. “Every so often” a collar was applied to the cable, and suspender cables were attached to them. To these suspenders, floor beams and girders were to be fastened, and on them the double deck of the bridge was to be built up.
To-day, at any time, you can see a procession of trucks plodding over the bridge, with a string of hurrying trolleys and rushing elevated trains loaded to the limit of capacity with human freight, all supported by the combined strength of those thread-like wires that were spun by human spiders across the East River.