Page:Arthur B Reeve - The Dream Doctor.djvu/382

, pressed my arm. I turned quickly to see if she needed assistance. Her face was radiant. All the fees for big cases in the world could never have compensated Kennedy for the mute, unrestrained gratitude which the little woman shot at him.

Kennedy saw it, and in the quick shifting of his eyes to my face, I read that he relied on me to take care of Mrs. Godwin while he plunged again into the clearing up of the mystery.

"I have here the will—the second one," he snapped out, turning and facing the others in the room.

Craig turned a switch in an apparatus which his students had brought from New York. From a tube on the table came a peculiar bluish light.

"This," he explained, "is a source of ultraviolet rays. They are not the bluish light which you see, but rays contained in it which you can not see.

"Ultraviolet rays have recently been found very valuable in the examination of questioned documents. By the use of a lens made of quartz covered with a thin film of metallic silver, there has been developed a practical means of making photographs by the invisible rays of light above the spectrum—these ultraviolet rays. The quartz lens is necessary, because these rays will not pass through ordinary glass, while the silver film acts as a screen to cut off the ordinary light rays and those below the spectrum. By this means, most white objects are photographed black and even transparent objects like glass are black.

"I obtained the copy of this will, but under the condition from the surrogate that absolutely nothing must be done to it to change a fibre of the paper or