434 



Popular Science Monthly 



At left: The Bettini 

 camera with plate-holding 

 magazines in position for 

 taking motion- pictures. 

 The amateur may make 

 his own negatives and 

 develop positives for pro- 

 jection upon the screen. 

 A special device can be 

 fitted to this camera 

 for taking photographs 



At right: The disk projec 

 tor intended as a toy for 

 children. Here the mo- 

 tion-pictures are printed 

 on a flexible non-inflam- 

 mable disk instead of on 

 glass. The disk may be 

 held stationary for any 

 length of time required for 

 a detailed study or adjust- 

 ment of any of the pictures 



and the lantern for projecting it on the 

 screen) are moved across each succeeding 

 row in the opposite direction. In other 

 words, the lens or lantern is moved from 

 right to left across the first row of images 

 until it comes to the last square, when the 

 glass plate is automatically fed downward 

 to bring the second row into position, and 

 so on until the plate has been used. 

 The feed of the Bettini apparatus is 

 so constant that the pictures are 

 projected with very little flicker. 



The synchronizing of the plate 

 movement and the lens move- 

 ment is so perfect that there 

 is no "jumping" when the 

 glass plate is shifted down 

 from row to row. Further- 

 more, one plate may quickly 

 follow another, so that the 

 longest picture may be pro- 

 jected as easily as with the 

 celluloid film. 



The optical principle of the 

 Bettini plate camera and pro- 

 jector — the principle on which 

 all the patents are based — 

 may be understood from the accom- 

 panying diagram. The objective with its 

 prism is mounted on one side of the plate, 

 while on the other side is a second prism on 

 the longitudinal axis of the lantern con- 

 denser. The light from the lantern passes 

 through a condenser, strikes a prism iand is 

 there bent at right angles toward the 

 image on the plate. Passing through the 

 image on the plate it enters the lens to 



which the prism is attached, and once more 

 the ray is deflected at right angles so as to 

 be thrown upon the screen. 



Any image on a Bettini plate 

 can be enlarged and printed in 

 a few seconds. The plates may 

 be run backwards, thus afford- 

 ing no end of amusement. 

 Circular sheets of non-inflam- 

 mable material may be used 

 instead of glass plates, and cir- 

 cular and square plates may 

 be made from standard films. 



The combined camera 

 and projector. The plate 

 movement and the lens 

 movement are so perfect 

 that there is no "jumping" 

 when the plate is shifted 

 down from row to row 



A Trip to the North Pole 

 by Submarine 



AS early as 1899, Mr. Simon 

 Lake, the inventor of the 

 "Lake" type of submarine, 

 proposed and planned a sub- 

 marine for sailing under the ice 

 of the Arctic waters to the 

 North Pole. It was realized 

 that this way of traveling 

 would save an explorer many 

 tedious months and would in- 

 crease the assurance of his reaching his 

 destination. But the submarine was in its 

 early stage of development and the carry- 

 ing out of the plan never got much further 

 than a few experiments. The extensive im- 

 provements in the submarine since that 

 time, however, have again brought this mat- 

 ter up for serious consideration. The sub- 

 marine required need not be very much dif- 

 ferent from the Deutschland, it is said. 



