Stalactites and Stalagmites. When the sun is just warm enough to melt the snow on the roof of a building, icicles form along the eaves, sometimes of great size. If the run of water be sufficient, similar needles of ice build up from the ground directly under the drip of those above. In the course of centuries water passing through limestone absorbs a great deal of lime. Wherever it trickles through the roof of a limestone cavern it deposits a part of this lime in formations like those of icicles just described. The same process in a way takes place in a teakettle in which hard water is boiled. The icicle-shaped formations of lime that hang from the roof of a cave are called stalactites; those rising from the floor are stalagmites. The stalactite is apt to be more regular and pointed in form than the masses which accumulate on the floor. They are sometimes white and nearly transparent, and again they are tinted with pale yellow and brown colors. The caves of Cuba, Virginia, Kentucky, and southern Indiana are noted for these formations. The enormous chambers of the Mammoth and Wyandotte caves contain fine specimens.