Railroads and Boat Landing Prairie Du Chien, Wisconsin
Prairie du Chien, which is the second oldest city in the State, justly claims to be the point at which has transpired the first of many important events of the past century, in the great northwest. Long before the introduction of our present system of railways, boats and ferries were employed at this point to transport men and their merchandise to the western shores of the Mississippi, that settlement might be effected on the vast and almost unlimited scope of fertile prairie lands beyond this great water course.
Milwaukee, the metropolis of the State, owes its growth largely to the fact that it is situated at the nearest accessible point on the western shore of Lake Michigan from Prairie du Chien.
The opening of the road was a great cause of rejoicing and every one felt the inspiration. When it is remembered the difficulty was experienced before this time by the residents in going to and fro from Milwaukee and Chicago, and depending, as they were obliged to do, entirely on the Mississippi river for a market, and in the winter season entirely cut off except by land transportation; it will be seen that there was much cause for enthusiasm. Its influence on Prairie du Chien and the states of Iowa and Minnesota was of a marked character, inducing immigration, and benefiting all classes of business enterprise. One newspaper states that three hundred and twenty-seven houses were erected here this year, and besides many other public improvements.
The Chicago, Milwaukee & St. Paul road made Prairie du Chien a division point and has a large shop and roundhouse in that part of the city, known as "Lower Town." Their main yards and depot buildings after 1862, being located just west from the main portion of the city.
The Pile Pontoon Railway Bridge
This bridge is a part of the "transfer" line of railway spanning the waters of the Mississippi river, and connecting Prairie du Chien with North McGregor, which is situated on the Iowa bank of the stream. This invention is indeed one of the triumphs of the nineteenth century, which has attracted the attention of civil engineers and master workmen, the world over, and therefore justly claims a minute description in this connection. It is the invention of John Lawler, of Prairie du Chien. It was patented by him Aug. 11, 1874, but its construction was fully completed on the 15th of the previous April. The entire length of the bridge is 8,000 feet, crossing both channels of the Mississippi river and an intervening island at Prairie du Chien, thus connecting the Iowa and Wisconsin divisions of the Chicago, Milwaukee & St. Paul railway. It is constructed in two parts; the pile or stationary part, and the pontoon or movable part, consisting of two floating "draws," one in each channel, which, when closed, form an unbroken track, permitting safe and rapid transfer of trains, and when open affording a clear space of 400 feet in either channel, allowing the widest rafts and largest tows that float the river to pass with ease and safety at all times and in any kind of weather. The pile part of this bridge is of the ordinary construction, used by all railways in crossing low, marshy ground and shallow streams. The "draw" over each channel consists of one pontoon, 408 feet long, twenty-eight feet beam, and four feet high and twelve-inch draft. It has great buoyancy and strength, being provided with a Howe truss passing through its entire length. When trains are passing over, the draft is increased to eighteen inches. The extreme rise and fall of the river is twenty-one feet, and to overcome the variation in height of the places between the pile bridge and pontoon, aprons or movable tracks are provided, which are adjusted by means of powerful hydraulic jacks and movable blocks, which are operated by the men in charge of the bridge. The connections between the ends of these aprons and the track of the bridge is a simple devise, counterbalanced by equal weights, so that one man clamps and unclamps the end of the pontoon, when swung in or out of its position. The pontoon "draws" are each attached at one end to a pile, placed twenty-eight feet back from the end of the stationary bridge, by an arm as long as the draw is wide. About this pile or pivot the "draw" swings, describing in its course an arc of ninety degrees, and when open lies at right angles to the pile, and entirely out of the channel. The "draw" openings of this bridge are the only ones on the Mississippi river wide enough to permit a steamer and large raft to pass through in one section.
The closing and opening of each pontoon is effected by an engine of twenty-horse power, situated on the "draw," working
a simple winch around which is wound a chain, the extremities of which are secured to a cluster of piles above, and below the pontoon, so fixed as to give a diagonal lead across the stream. The bridge opens with the current in one minute, and closes against the current in about three minutes, without showing any undue strain, or requiring the application of more than five-horse power. In relation to the passage of trains, it has been proved to afford greater
security than the old style of draw bridges, for the pontoon is capable of floating a weight equal to six times that of the heaviest trains.
At this date (1884) the inventor and builder, John Lawler, together with his sons, still owns and operates the bridge and receives a certain amount per car from the railway company, for all freight and passenger trains, which pass over the Mississippi river.
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