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Page:Popular Science Monthly Volume 90.djvu/898

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882

Protecting Canal Zone Buildings with an Oil Moat for Insects

IN the Panama Canal Zone ants, lizards, snakes and creeping insects are so numerous and so pestiferous that it is difficult to keep them from climbing up foundation pillars and invading houses. Hence concrete gut- ters are provided for all posts. Of course, the ants can crawl up the concrete as freely as they can up wood, but when they reach the land- ing platform of the gutter they find a miniature lake of oil-insecticide awaiting them. They never get be- yond this little moat.

To prevent the fre- quent rains from running into the insecticide, a bungalow top, also of concrete, forms a sheltering roof for the gutter.

��Popular Science Monthly

���Enveloping Trees in Freezers to Study Temperature Effects

A CONTRIVANCE designed to freeze whole trees has been constructed at the Utah Agricultural College, Logan, Utah, to aid in experimental work intended to discover, under actual orchard condi- tions, the frost danger point.

The contrivance is very similar in princi-

GALVAN12E0 IRON" TANK

��5ELF REGISTERING THERMOMETER

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���pie to the old fashioned ice-cream freezer. It consists of a huge galvanized iron tank, large enough to enclose an entire tree. This tank is divided into halves and each half is fastened to a plank base, so con- structed that a half can be placed on either side of the tree to be frozen, and the two parts drawn to- gether, completely enclosing the tree. ' The tank is double walled, with a four-inch space between the walls. A large lid covers the tank and rests on the inner wall. Ice and salt are packed in between the walls and over the lid. The temperature in- side is regulated by pumping in cold or warm air, and the air inside is kept stirred by an elec- trically driven fan. Four self-registering Weather Bureau thermometers and a ther- mograph, hung from different branches of the tree, keep an accurate record of the temperature within the tank.

The resistance of buds to frost can be accurately determined by this method and data collected that will tell when smudge pots or other artificial means of orchard heating should be used to save the fruit crop. ,

The tree is not injured by the process, since care is taken and constant watch is kept to prevent the danger point from being reached.

��The insecti- cide in the gutter is pro- tected from rain by a cement roof

��AIR STIRRED 6Y ELECTRIC FAN

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The tank is double-walled, with a four-inch space between walls. In this space snow and ice are packed just as in a cream freezer

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to a plank base. These are drawn together and a large lid covers both halves when joined

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