“The what?”
“Diaphragm,” repeated Allan.
“How do you spell it?”
“I don’t think I can spell it. What do you always want to spell things for? It begins with a d-i-a and then gets all mixed up—ho, here it is in the directions, if you must spell it—‘d-i-a-p-h-r-a-g-m.’”
“What does it do?”
Allan was turning the disk. “Look,” he said; and they saw that the diaphragm had three holes in it, and that any one of these holes could be brought opposite the centre of the lens.
“I don’t see how anything could possibly get through that!” exclaimed McConnell, staring at the smallest opening.
“Why,” said Allan, “Owen says you can photograph through a pinhole—with a pinhole, I think he said.”
“He didn’t mean without a lens, did he?” demanded McConnell, incredulously.
“That’s an old trick, McConnell,” said Dr. Hartel in the doorway. “I photographed with a pinhole when I was a lad.”