"Electricity?" repeated the two chums, in questioning accents.
"Yes, from the battery. You see I couldn't sleep, and I often find a current of electricity is beneficial. I did not want to awaken Captain Wiggs with the buzz of my machine, for it makes quite a noise, so I brought it into this empty stateroom. I hope I didn't disturb you."
Mr. Ackerman did not wait for the boys to answer. Instead he continued:
"But I'm glad you came in. I want to take a stronger current, and it goes better if I have some one to share it with me. If you will be so kind, you can each take one of the tubes in your hand, and I will take hold of your other hands. Thus we will form a circle, with me in the center. I think I shall be able to get a current then, that will cause me to go to sleep."
The boys were a little apprehensive, for, though they had taken electric "shocks" at school, during the experiments, they did not care for the amusement. However, they did not like to refuse, so, rather gingerly, Fenn grasped one handle, and Frank the other. Mr. Ackerman then did something to the battery which made it buzz louder than ever.
"All ready," he announced, as he grasped Fenn's right hand in his left and Frank's left in his right.
The instant that he did so it seemed as if the trio had been hit by something. They all doubled up, the arms of the boys and the invalid jerking like the legs of a frog.
But there was no need for any one to let go. With an exclamation of great astonishment, Mr. Ackerman jerked his hands from the involuntary grip of the boys'. That at once broke the circuit, and the current ceased to have any effect. The machine was still buzzing away, however.
"Oh, dear! Oh, dear!" murmured the invalid. "I meant to turn on the weak current, and I turned on the strong one! Did you get bad shocks, boys?"
"Did we!" exclaimed Fenn. "Say, it feels as if I had eaten some strong horse-radish by mistake."
"It seems as if a mule kicked me," remarked Frank, rubbing his arms.
"I'm very sorry," apologized Mr. Ackerman. "I really did not intend that. I hope you believe I did not." He seemed quite distressed over the happening.
"That's all right," spoke Fenn, good-naturedly. "We know it was an accident."