X-RAY MOTION PICTURES 143 



between exposures might vary % 6 of an inch but at 

 the instant of exposure, two %2" holes were punched 

 in the upper corners of each picture. These holes 

 were perfectly synchronized with the location of the 

 picture on the film so when it was copied to standard 

 35 mm. film, a pilot pin went into each hole, giving 

 me a perfectly steady picture, so the error of distance 

 apart did not affect the picture. An X-ray camera 

 uses no lens. The rays from the tube travel in a per- 

 fectly straight line. So far it has been found impos- 

 sible to bend them, so in taking a picture the subject 

 is placed as close as possible to the film. The light 

 shines through it, making a shadow-graph on the 

 film, bones casting a different shadow from flesh, 

 etc. That is why it is necessary to use a larger film 

 than the subject shadow-graphed. 



My first picture was of a rose bud opening. I made 

 a test exposure with the low voltage tube set at 9,000 

 volts. It took two minutes and twenty seconds so I 

 started the camera at five minute intervals, starting 

 one of the regular Bell and Howell cameras at the 

 same time with Mazda light on a similar bud. The 

 X-ray camera would pull the film forward in this 

 case three inches. I was using a four-inch roll so made 

 3x4 shadow-graphs, then the light came on, lasted 

 2' 20", went off, the film pulled forward 3", winding 

 up in the upper magazine. This was kept up for 



