ARTIFICIAL DRAFT)

Chimneys are built of brick or iron lined with brick, or of brick with an iron skeleton, or of iron alone. Usual sections are round, square, or star-shaped. Many have an inner lining not bonded to the outer shell, so that unequal expansion shall not tend to wreck the structure. High chimneys are designed to resist a Chilognatha (MILLIPEDES, or You sand-LEGS). Myria- pods with nearly cylindrical body. Each segment, except the anterior ones, bears two pairs of legs. The antennæ have only seven joints, the mouth parts are adapted to masticate vege- | horizontal wind pre ure of 40 to 50 lbs. per sq. foot. The Chimney at Halsbrucke. highest chimney in the world is at Halsbrücke in Saxony: the base is 40 ft. sq. and 28 ft. high, and the chimney shaft on this is circular with an inside diameter of 15.7 ft.; the height is 453 ft. At Kearney, N. J., is a chimney 335 ft. high.