IO

DESCRIPTION OF THE MACHINERY HALL.

for ventilation. Louvre ventilators are introduced in continuous lengths over boththe avenues and the aisles. The building is lit entirely by side light.

The motive power is furnished by a Corliss engine of 1400 horse power. Thereare eight main lines of shafting, extending almost the entire length of the structure,and countershafts are introduced into the aisles where needed. The hangers areattached at the height of 20 feet from the floor.

The annex for hydraulic machines contains a tank 60 feet by 160 feet, with depthof water of 10 feet. In this hydraulic machinery is exhibited in full operation. Atthe south end of this tank is a waterfall 35 feet high by 40 feet wide, supplied fromthe tank by the pumps upon exhibition.

The contract in the erection of Machinery Hall was made January 27th, 1875,and the building was begun forthwith, and finished October 1st, 1875. The cost was$542,300. The exhibition area covers about 14 acres.

KEY TO THE NOTATION.

THE location of objects in the Machinery Building is shown by a letter and figure,indicating the nearest column of the building. The letters—A, B, C, to F—designatethe successive ranges of columns, proceeding northward from the southern wallacross the width of the building; the figures, the number of the column in eachrange, counting westwardly from the eastern wall, the entire length of the building,from 1 to 88. Thus C 5 is the column in the third range from the south, and thefifth from the eastern end of the building. The northwesternmost column is F 88.

The class of the classification (see page 13) to which each exhibit belongs is in-dicated by the small figures at the end of the line.