Popular Science Monthly 



387 



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 



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. 



