Page:Popular Science Monthly Volume 90.djvu/108

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��Popular Science Monthly

��What Jack Frost Did with a Fountain of Running Water

JACK FROST is our deftest and daintiest architect. He builds millions of structures each year and draws other billions of patterns. The prob- lem of being original never bothers him. Each snowfiake is an artistic triumph ; each frosted window-pane is differ- ent in its every detail from the countless billions which have appeared since the beginning of time. No, Jack Frost doesn't bother about patent and copy- right laws. If he were so inclined he could secure a patent on every snowflake that falls.

The accompanying illustra- tion below shows what he has done in the way of an ice cone. Next winter he will make one in the same place — and make it so it won't infringe on the rights of this one. The ma- terial he worked with here was

���This great stalagmite of ice was formed drip by drip

��a spring which gushed up into a fountain. As the ice formed, the water was raised higher and higher from pressure under- neath until the cone was formed. If it could be examined or if a cross-section of it could be obtained it would probably be found to have a hollow center, growing gradually smaller and smaller in diameter. The fact that the running water had consider- able pressure from a high fountain head and that water will find its level made it possible for Jack Frost to fashion the cone. However, the fountain isn't so important after all. He could do equally well with a stream of water from a garden hose, if it were made to spout upward in the same manner and left long enough in that posi- tion in weather of the proper temperature.

���The cone was formed gradually from circumfer- ence to center until the highest peak was reached

��An Icicle Which "Sprouted" Over Night

WHO ever heard of an icicle growing upside down? There was one particular icicle which was not contented with the usual order of things and accordingly decided to grow from the bottom up. The water as it fell drop by drop from a faucet one very cold night in Beaufort, North Car- olina, froze before it could travel very far on its journey. Slowly, as the water froze, the icicle grew, and when morning came the "sprout" had reached a height of twenty inches.

It is interesting to note that the huge "icicles" of rock which are often found in caves of the mountainous districts of the United States are formed in a way that is very much similar to the way this icicle was forrned. Underground streams of water, which carry various kinds of rock in solu- tion with them, frequently empty into a cave at its top. The water dropping gradually from the roof of the cave, slowly evaporates and leaves the rock in its solid form. As drop after drop falls and evaporates, a giant "icicle" of rock is formed which is often made up of many attract- ive colors, though yellow, mellowing in to brown is the most common. Somestalag- mites, as they are called, when the base rests upon the ground, or bottom, of the cave, take hundreds of years to form. Often they meet stalactites (sim- ilar formations with the base attached to the ceiling or high projection in a cave) and thus form a con- tinuous column. The Mammoth Cave in Kentucky contains many specimens both of stalactites and stalagmites.

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