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50 Years Ago

From the October 17, 1931, issue

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MATERNAL CARES MULTIPLY WITH COMING OF COLD

Winter has breathed a hint of its coming already, in puffs of frosty air that make us forget the heat of summer that is gone, even of the unseasonable hot spell of early September. But the coming of the cold bodes only ill for the cold-blooded creatures of field and forest. They have but two alternatives: to die, leaving eggs, larvae or pupae in safe places to carry on the life of the species next year; or to endure the cold and drought in the death-like slumber of hibernation.

Spiders take both courses. Some species leave their egg-balls hidden in crevices or suspended in webs and crawl away to die. Others drag their egg-balls with them and hibernate, mother and unhatched young sharing the same hiding places. Thus one will see, every autumn, spiders dragging their thousand-fold cradles with them.

The particular specimen shown on the cover is a close-up of one of the fiercest and most formidable of the hunting spiders, a member of the large genus Lycosa, better known as the wolf spiders. This one was photographed in an attitude of jealous maternal watchfulness by Cornelia Clarke.

RESEARCH AIDED BY MACHINE SOLVING DIFFICULT EQUATIONS

A new machine that can solve the complex mathematical problems arising in the course of scientific research has been made by Prof. V. Bush at the Massachusetts Institute of Technology.

The differential analyzer, as Prof. Bush calls his mechanical thinker, will do for the advanced branches of science and engineering what the adding machine has done for business accounting methods.

MAGNESIUM CEMENT DEVELOPED HAVING HARDNESS OF GRANITE

The expression as hard as rock will have to be changed to as hard as cement if the experiments of Dr. Howard S. Lukens of the University of Pennsylvania Chemistry Department work out as he has reason to think they will. For 6 years Dr. Lukens has been working with a combination of magnesium oxide and magnesium chloride, and he now has a cement that has the tensile strength of 2000 pounds per square inch. It is as hard as granite.

The catch is that the cement so far can be used successfully only for interiors, for water does something to it and it disintegrates. However, it is now possible to fabricate a stable magnesium cement product that does not absorb moisture from the air, and that is something ordinary Portland cement has never overcome.

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