St. Nicholas/Volume 40/Number 5/Nature and Science/Bent
Bent by the sun
The towering Washington monument, solid as it is, cannot resist the heat of the sun, poured on its 
The Washington Monument, and in the foreground, its reflection in the water.
Courtesy of The Pennsylvania Railroad. southern side on a midsummer’s day, without a slight bending of the gigantic shaft, which is rendered perceptible by means of a copper wire, 174 feet long, hanging in the center of the structure, and carrying a plummet suspended in a vessel of water. At noon in summer the apex of the monument, 550 feet above the ground, is shifted, by expansion of the stone, a few hundredths of an inch toward the north. High winds cause perceptible motions of the plummet, and in still weather delicate vibrations of the crust of the earth, otherwise unperceived, are registered by it.—Scientific American.