a crushing strength of 50 tons per square foot. Above low water the cylindrical piers which are 49 feet in diameter at the top 55 feet at the bottom and 36 feet high consist of the strongest masonry the hearting being flat bedded Arbroath stone and the facing Aber deen granite. In each cylindrical pier there are 48 steel bolts1% inches in diameter and 24 feet longto hold down the bed plate and superstructure of the main spans. One of the Fife piers was built by aid of a tim ber and clay cofferdam and one by means of a half tide dam. At Inch Garvie much of the work of the shallow piers had to be done at low tide under great difficulties. The Queensferry Pier consists of a group of four cyl indrical caissons 70 feet in diameter at the bottom edge. Owing to the special conditions of the site the work differs in some respects from ordinary pneumatic caissons. The bed of the Forth at the Queensferry Pier is of very soft mud for a depth of from 20 feet to 35 feet when the bowlder clay is reached the surface of both the mud and the clay falling sharply toward the 200 feet deep channel between Queensferry and Inch Garvie. The caissons had to be floated out and sunk about one-third of a mile from shore in an expos ed seaway. To facilitate operations the caissons have double skins 7 feet 6 inches apart and vertical bulk heads between the skins. By filling the space between the skins with concrete to varying heights the irregu larity in the level of the bottom and the hardness of the mud could be to some extent compensated for as the weight brought upon the cutting edge of the caisson could be regulated as desired. Iron being cheap a liberal use was made of it in conjunction with concrete where masonry or brickwork might have been em ployed. Strong lattice girders and cross girders stiffen to the required extent the roof of the working chamber. These girders are subject to a heavy bending stress up ward and downward owing to the tide the range of which is about 20 feet. Thus i
Keywords:
crushing strength, 50 tons, square foot, low water, cylindrical piers, 49 feet, diameter, top 55 feet, bottom, 36 feet high consist, strongest masonry, hearting, flat bedded Arbroath stone, facing Aber deen granite, cylindrical pier, 48 steel bolts1% inches, diameter, 24 feet longto hold down, bed plate, superstructure, main spans, Fife piers, built, aid, tim ber, clay cofferdam, means, half tide dam, Inch Garvie, work, shallow piers, done, low tide under great difficulties, Queensferry Pier consists, group, four cyl indrical caissons 70 feet, diameter, bottom edge, Owing, special conditions, site, work differs, respects, ordinary pneumatic caissons, bed, Forth, Queensferry Pier, soft mud, depth, 20 feet, 35 feet, bowlder clay, reached, surface, mud, clay falling sharply, 200 feet deep channel, Queensferry, Inch Garvie, caissons, floated out, sunk, -third, mile, shore, expos ed seaway, facilitate operations, caissons, double skins 7 feet 6 inches apart, vertical bulk heads, skins, filling, space, skins, concrete, varying heights, irregu larity, level, bottom, hardness, mud, extent compensated, weight, upon, cutting edge, caisson, regulated, desired, Iron, cheap, liberal, conjunction, concrete, masonry, brickwork might, em ployed, Strong lattice girders, cross girders stiffen, required extent, roof, working chamber, girders, subject, heavy bending stress up ward, downward owing, tide, range, 20 feet, Thus , science, scientific, sciences, mind, health, tech, sustainability, publication, lab, sciam, sa, scientist, research, american, experiment, education, discovery, technology, analysis, magazine, u.s., insights, developments, weekly, broadsheet, inventor, innovation, inventions, patented, industrial revolution, emerging, trends, monthly magazine, united states, engravings, curious works, paper, discover, Scientific Paper, Weekly Journal, Practical Information, Art, Science, Mechanics, Chemistry, Manufactures, research, education, scientist, innovation, 19th century, vintage, america, Rufus M. Porter, 1845, journal, academic, newspaper illustrations, retro style, old-fashioned, media illustrations, victorian style, news, newspaperheadline, 19th century style, illustration, journalism
Image ID:
The watermark in the image will not appear on the final download.