“Though the box might have said, ‘by ruby light or no light,’” replied the Doctor. “There is no objection to your opening it by no light if you want to.”
“But we couldn’t see,” protested McConnell.
“You could feel, though,” the Doctor explained. “An old photographer told me that he always preferred to load his plate-holders in the dark. He trusted his touch with no light more than he did with a weak red light with which he sometimes let his eyes deceive him.”
“Deceive him how?” asked Allan.
“By letting him get a plate wrong side up.”
“Oh!” said Allan. He hadn’t thought to consider that the plates had a right and a wrong side.
“When you come to open your box,”—then the Doctor paused a moment. “Suppose, boys, that we go and load the plate-holders. We’ll go up to your room, Allan.”
“But how about the ruby light?”
“Oh, we shall soon fix that. Where is your bicycle lamp?”
Allan fetched the well-worn headlight of his wheel, and when it was lighted, the boys remarked that the side glasses were a rich red.