No. 20. MACHINERY HALL.

Size, 360 by 1402 feet; annex, 208 by 210 feet.

Engineers and Architects , Henry Pettit, Joseph M. Wilson, Philadelphia .Contractor , PHILIP QUIGLEY, Wilmington , Del .

Wrought and cast iro?i furnished by Pusey, Jones, & Co., Wilmington , Del.

Machinery Hall is located west of the intersection of Belmont and Elm ave-nues, at a distance of 542 feet from the west front of the Main Exhibition Building,and 274 feet from the north side of Elm avenue. The north front of the building isupon the same line as that of the Main Exhibition Building, thus presenting a front-age of 3824 feet from the east to the west ends of the exhibition buildings upon theprinciple avenue within the grounds.

The principal portion of the structure is one story in height, showing the maincornice upon the outside at 40 feet from the ground, the interior height to the top ofthe ventilators in the avenues being 70 feet, and in the aisles 40 feet. To break thelong lines upon the exterior, projections have been introduced -upon thefour sides, and the main entrances finished with facades, extending to 78 feet inheight. The east entrance forms the principal approach from street-cars, from theMain Exhibition Building, and from the Pennsylvania Railroad depot. Along thesouth side are the boiler houses and other buildings for special kinds of machinery.The west entrance affords the most direct communication with George’s Hill, whichpoint affords the best view of the entire exhibition grounds.

The arrangement of the ground plan shows two main avenues 90 feet wide by1360 feet long, with a central aisle between, and an aisle on either side. Each aisleis 60 feet in width ; the two avenues and three aisles making the total width of 360feet. At the centre of the building is a transept of 90 feet in width, which at thesouth end is prolonged beyond the Main Hall. This transept, beginning at 36 feetfrom the Main Hall and extending 268 feet, is flanked on either side by aisles of 60feet in width, and forms the annex for hydraulic machines. The promenades in theavenues are 15 feet in width, in the transept 25 feet, and in the aisles 10 feet. Allother walks extending across the building are 10 feet in width, and lead at either endto exit doors.

The foundations consist of piers of masonry. The superstructure consists of solidtimber columns supporting roof trusses, constructed with straight wooden principalsand wrought iron ties and struts. As a general rule, the columns are placed length-wise of the building, at the uniform distance apart of 16 feet. The columns are 40feet high to the heel block of the 90 feet span roof trusses over the avenues, and theysupport the heel of the 60 feet spans over the aisles at the height of 20 feet. Theouter walls are built of masonry to a height of five feet, and above that are com-posed of glazed sash placed between the columns. Portions of the sash are movable

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