Page:Popular Science Monthly Volume 91.djvu/403

 Popular Science Monthly

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��fifty dollars each exclusive of labor cost.

The bomb is about six feet six inches long and the diameter of the war head is about six inches. At its upper end there is a stabilizer which keeps it true to its course. The bomb is carried suspended in a horizon- tal position beneath the aircraft. When released, the end containing the explosive, being the heaviest, drops first, bringing the apparatus into a verti- cal position.

Having assumed this position, the action of the air operates a valve which re- leases a tele- scoped tube to which the stabilizer is attached. This extends the device to a full length of about ten and one-half feet. At the same time, the detonat- ing rod is re- leased from its position in the center of the bomb until it protrudes a distance of about six feet six inches below the war head, ready to set off the detonator as soon as its point touches the earth. The manner in which the detonator operates and other features of the bomb are of great military value and are being kept a secret.

It is known, however, that up until the time the bomb is dropped from the air- craft carrying it, the detonator is held in such a position that it is impossible to discharge it, so that no matter how much explosive is in the war head there is no danger. Only after the bomb starts on its way toward the earth does the detonator become operative. To demonstrate its safety features the bomb was riddled with rifle bullets during a test in England. It failed to explode.

According to Representative Tilson of Connecticut, the Government is now de- veloping a bomb of this type to drop on

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� ��Young girls as dental hygienists examining the teeth of several boys and girls in the Vanderbilt Clinic, New York city

��submarines. For this kind of work the nose of the bomb is made to operate if it strikes a hard substance and not to operate if it hits water. In the tail of the device is a timing mechanism that can be set to let it go to any depth below the surface of the water before it explodes. Should it hit any solid object on or below

the top of the water it will explode instantly, but if it con- t i n u e s going down through the water, when it reaches the depth for which it is set, it will explode automatical- ly at that depth just as if it were on land. In this way it be- comes the most threat- ening men- ace to the submarine yet devised.

��The Dental Hygienist Takes Her Place Beside the Dentist

WOMEN have assisted dentists for many years, but not until recently did it become necessary for a girl to attend a three months' course of training and then pass an examination before she could take her place beside the dentist and help him with his work. The accompanying illustra- tion shows the graduating class of the Vanderbilt Clinic, in New York city, ex- amining and cleaning the teeth of several youthful patients.

These girls study and do practical work in the laboratory for three months. After that they take an examination; if they pass it they are given the title of "dental hygienist." A great deal of minor work is entrusted to them, such as treating gums, cleaning the teeth and administering gas. None but high school or college graduates are accepted for training.

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