The Popular Science Monthly

for July

Are mine fields a real defense against submarines? Ships are being torpedoed every day in the mined English Channel and in harbors seemingly impregnable because of the extensive mine fields that guard the entrance. Could this happen in New York Harbor?

The Mine That Hears

One of the most prominent of our engineers has invented a system to destroy instantly any submarine ichich might attempt to pene- trate into our harbors. He describes this wonderful invention in the Jidy Popular Science Monthly.

How to Camp

Are you going camping this summer? Next month will appear an article on this subject which ivill give new ideas to even the most seasoned camper.

What Sailors Don't Know About SaiHng

Most yachtsmen think that they know how to sail a boat. They don't. Professor H. A. Everett, of Johns Hopkins University has analyzed the science of sailing a boat, and shojvs in the July issue just why most men handle their boats badly.

The Voice Typewriter; Talk and It Writes

Other features are: " Automobile Repair

Kinks, "A Typewriter That Obeys the

Human Voice," "^4 New Armor Protection

for Ships," and — but ivhy continue? There

are three hundred more.

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