WIRE ROPE IN THE QUARRY
It was in the summer of 1869 that John A. Roebling died. The second day of January, 1870, saw the actual work of construction begun, when laborers started to clear away to prepare for the foundations of the Brooklyn tower. From that day forward, through a baker’s dozen of years, there was no rest, though there was plenty of interruption. Until the job was ended Washington A. Roebling simply lived the Brooklyn Bridge. It was a colossal job, punctuated with changes and problems and complications, but it went forward. The landmarks of a bygone age, old houses of historic memory on the water fronts of both cities, vanished silently and where they had been, by and by there grew piles of masonry to form the approaches. From the huge caissons over against either shore rose the towers, tall and grim, which were to carry the cables. In due time they stood complete, with their broad bases welded to the rock by an ingenious bond of stone and concrete in the river’s bed, and their crests nearly three hundred feet above the top of the tide. A hundred and nineteen feet—and three inches, to be precise—above the water opened the two tall arches in each tower, stretching upward one hundred and seventeen feet in air. It was through these the bridge proper was to pass, with its gangways for horse and foot and railway traffic.
COULD THOSE SLENDER TOWERS CARRY THE GREAT LOAD?
The hurrying people of New York and Brooklyn watched the thing grow and wondered fearfully whether the slender towers would stand the strain. In Harper’s Magazine for May, 1883, now itself yellowed by age, is an exhaustive article concerning the Brooklyn Bridge, in which one is told at length and with an engineer’s exactness, the steps by which the achievement was brought, after thirteen laborious years, to proud completion.
Even to the curious layman the details are no longer of insistent interest. One thing is emphasized, however, which well as we know it now can never cease to hold the mind in a certain wonder—that all the weight and solidity and massiveness are in the towers, the foundations and the long expanses of stone work, which stretching inland nearly a thousand feet, serve to guard and strengthen the anchorage for the cables which are the working force. The rest is wire, for the most part; wire, slender by contrast and against the background of the sky, but endowed with great strength by care and skill in fabrication. John A. Roebling and his son had staked their name and their future on the strength and quality of Roebling wire.
In that long ago story of the Brooklyn Bridge, there is written the lesson that clear thinking and courage and perseverance can accomplish the seemingly impossible. What traveler over those high-hung roadways ever stops to ask himself how those great round cables, stretched in long, inverted arches above the surge of the river traffic, were ever put in place? They are today simply a part of the stage setting of a busy life, like the river itself.
HOW THE GREAT CABLES WERE MADE
Each of these cables consists of nineteen strands of about two hundred and seventy-eight No. 8 B. W. G. wires each, and each wire is continuous in its strand, like the yarns in a skein, traveling eternally to Brooklyn and back, up over the top of one tower, down in a long curve above the tideway, up to the other tower and down again, to be gripped and carried by links, like a chain, down to the everlasting clutch of the rock and concrete-bound anchorage. Each skein is a million feet long—nearly two hundred miles—and still men talk of “Oriental patience.”
There is no twist in these ponderous cables, as there is in a wire rope. Every reach of wire lies flat and separate, and when all were in place they were laboriously bound together, first the strands, then when all the strands were up, the whole fabric, into cylindrical form. There are other strange things about these cables; one is that they make practically no strain on the towers save to sustain their weight. Another is that the long storm cables that radiate downward from the top of the towers to the bridge floor, for a space of four hundred feet inside and outside each tower, are themselves calculated to sustain, if need be, the imposed weight for that distance. So that the margin of safety in this seeming web-like structure is far in excess of what timid imaginations have pictured. That was a cardinal feature in all John A. Roebling’s plans. He left a safety margin many times greater than the load. It has been an open secret for years that the Brooklyn Bridge has been unwisely taxed, but he knew it would be.
STRINGING THE CABLES ACROSS THE EAST RIVER