Tombstone epitaph., 1892-05-08
A MAMMOTH STRUCTURE.
The Wonderful Accomplishment of
 Mechanical Science.
How the Great Building for Manufactures and Liberal Arts at the Worlds Fair Was Planned-A Monster
 Derrick.

It is in its present stage of eonstruc- tion that the mammoth building for the manufactures and liberal arts at the worlds fair is most curious and inter esting, says Harper's Weekly. They are now at work on the big derrick. or ''traveler," as it is called. and the dimen- sions of this engine are suggestive of the tremendous proportions the building itself will assume as it hears compile ton. The great Eads bridge at St Louis is a remarkable structure, and one would fancy that building con taining more iron and steel than that embraced in its mighty arches must be a rare building indeed. In the nanu- factures building will be used 400 tons more of metal than the amount used by Mir. Eads' engineers New Workers know what Brooklyn bridge looks like. With the metal to be used in the liberal arts building two such bridges could be built, and there would still remain as much as 2,400 tons unused. To be more exact, upwards of 12,000,0o0 pounds of steel and iron will be consumed by the constructionists in the work of putting the liberal arts hall together.
 The plans for this the most extensive building ever attempted by man were prepared by Mir. George B. Post, of New York. The trusses that will sup port the roof are the largest in the world. There will be a clear span of SS6 feet from pillar to pillar. When the New Yorker stated that span of this proportion would be used. archi- a1 A,,t Ia, ( the idea, and said that this was ideal construction. But the enterprise was not submitted solely to builders of houses It was point that was not all included in the studies of architecture. It more nearly approaches bridge en- gineering. This is true of more than one building planned for the Columbian exposition. The bridge engineers were consulted. made their realculations, looked wise, closed their eyes as if in deep thought, and then pronounced: Tt cdH be done, but it will cost q great fortune
 in dollars
 Mir. Post was vindicated. and the worlds fair treasurer undertook to do the rest. The contracts were let to Pittsburgh company, and now they are demonstrating the accuracy of the mathematics by literally doing the work. But there was another problem land not a small one) to be solved before the iron and steel were made ready. Given the plans and the material, how could this 5000 tons of metal be lifted into position? There are 26 main trusses, each weighing POO tons, and these are to form the bases for the roof spans. To lift mass of material weighing 200 tons. and to handle it with the pre- cision and accuracy necessary for the niceties of Mir. Posts plans, require no common enginery. And no common enginery is brought into play here. It
 was a month ago that the builders be- gan the work of constructing the engine which was to carry these immense masses of metal as easily as an athlete swings dumb-bel. It was now almost | finished-a derrick 255 feet in height, { and S6s feet in length. It is built with | four uprights at the corners, that are
 jointed at sections of 70 feet by heavy
 cross beams, making the skeleton. For
 the stays are used as ropes of steel that are strung diagonally. Then there are ! V trusses that, being bolted and
 mortised to the cross beams, insure the strength of the structure.
 The traveller" rests on a foundation
 as stable and as solid as may be. A strip of the great floor was torn up, and piles in three rows were driven in along
 the line of the track which the derrick \ is to follow. Caps of timber 12 inches
 square, on which are placed 1Oo-pound steel rails, make track. Purchase will be had in the great cranes that will be rigged on the top of the traveller" :" ! The heaviest tackle obtainable will be i used in the working of these cranes A stationary engine will be used to move
 the derrick along the track.
 1 Now that this great derrick is ready,
 it is expected that the building itself
 will grow rapidly. In this case the prep
 a-a.ion for the work is almost as great
 an undertaking as the work itself.