For moving the spans from the launching ways to the piers. four barges were used. on which fulsework of timbers was built up to a proper height so that with a span on the barges the shoe of the span would be a few inches above the tops of the piers. When ready for moving. water was pumped into the seows supporting the fnlsework and they were floated underneath the span between the launching ways. Blocking was then placed between the falsework on the scows and the under part of the span so as to provide proper bearing, and the water pumped out of the scows, so lifting the span 011' the ways. The span floating on the barges was then towed out to position over the piers by
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ERECTING THE SUSPERSTRUCTURE METALWORK.
View of launching ways and spans ready to be transported as seen from the river. One of the barges for carrying the span may be seen to the left.
steamboats and tugs and water was pumped into the scows, lowering them and bringing the span to rest on the piers, and finally entirely releasing the seows, which were then taken back for another span.
The erection of the towers and other portions of the structure were by methods not unusual in steel erection, except that for the Oregon and Columbia Slough spans the material was all floated near to position on scows and erected from them. The
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