"It is a one-twelfth objective," replied the other, as he screwed the lens firmly down upon the cover glass, and thus embedded it, so to speak, in the globule of cedar oil.
"It is necessary," said he, "that the specimen be observed through the oil because the lens must be brought down directly upon the glass; without the oil the glass would be scratched and the whole thing ruined."
Then he set himself to the close study of what the tiny lens made plain; in a few moments he lifted his head with an exclamation of triumph.
"I have it!" he cried.
"What have you found?" asked Fuller eagerly.
"Evidence," answered Ashton-Kirk, triumphantly, "that will enable me to lay my hand upon the person who searched the library and clothing of Dr. Morse."
"The murderer?"
"Perhaps he is that also—who knows?"
"But," demanded Fuller, "I don't quite understand."
Ashton-Kirk waved his hand toward the microscope, and Fuller applied his eye to it.