Ojo, however, had kept his eyes fixed upon the body of the tin Emperor, and now he noticed that under the joint of his left knee a tiny drop of oil was forming.

He watched this drop of oil with a fast-beating heart, and feeling in his pocket brought out a tiny vial of crystal, which he held secreted in his hand.
Presently the Tin Woodman changed his position, and at once Ojo, to the astonishment of all, dropped to the floor and held his crystal vial under the Emperor's knee joint.

Just then the drop of oil fell, and the boy caught it in his bottle and immediately corked it tight.

Then, with a red face and embarrassed manner, he rose to confront the others.
"What in the world were you doing ?" asked the Tin Woodman.
"I caught a drop of oil that fell from your knee-joint," confessed Ojo.
"A drop of oil!" exclaimed the Tin Woodman.

"Dear me, how careless my valet must have been in oiling me this morning.