Popular Science Monthly 



529 



Fun With Pictures of Your Friends 



IF you would like to have a little fun 

 with your friends, try enlarging a 

 group negative or single figure after this 

 fashion : First place the negative in the 

 enlarging frame in the usual manner. 

 After the desired size of print has l)een 

 decided upon and focus made for size, 

 tip the frame or sliding-board (on which 

 sensitized paper is placed) gradually 

 backward, until the persons or scenes 

 assume fantastic shapes. The best angle 

 of the board will probably be around 

 forty-five degrees, although some nega- 

 tives require a greater angle to change 

 them. 



A print from the negative of your thin 

 friend will reveal him as a very stout 

 person, but without losing the facial like- 

 ness in the process. By tipping the 

 board backward, everything seen in the 



Diagram showing the arrangement of the 

 sliding - board for making trick pictures 



negative, is lengthened, so that the fat 

 man becomes a tall, thin person and a 

 stubby tower becomes a factory chimney. 

 The length of exposure needed will be 

 found to be about the same as when the 

 board is in the normal position. Dura- 

 tion of exposure depends on the size of 

 the stop used. It is not necessary to 



own an expensive enlarging outfit, since 

 the trick can be done on anything from 

 a "Brownie" to the professional appa- 

 ratus. Try it on your friends. 



Tip your sliding-board at forty-five degrees 



sidewise and you make the whole world rotund 



and happy 



If the tilt of the board is the length of 



the picture, thinness becomes an 



attribute of all 



A Metal- Vapor Light That Is White 



ANE^^' vapor lamp employing the 

 vapor from metals has been 

 patented by a German scientist. Zinc 

 chloride and zinc bromide have been 

 used and give the best results at at- 

 mospheric pressure. As in the mercury- 

 \apor arc, the inclusion of air or other 

 foreign gases in the tube is 

 prejudicial. On the other hand, 

 an arc in an atmosphere of 

 aluminium chloride or titanium 

 chloride is more stable, and an 

 admixture of nitrogen is harm- 

 less. Oxygen, however, must be 

 excluded. It is stated that the 

 color of the light is white, and 

 that the efficiency is in the neigh- 

 l)orhood of that of the mercury- 

 vapor lamp. 



The fact that the light is white 

 will greatly add to the importance 

 of the lamp, since there are many 

 uses which demand such illumina- 

 tion. 



