"They seemed to be constructed for use on ordinary electric power. But not the power supplied by Calthedra's dynamoes. I'll have to step up the frequency."
He opened a wall switchboard and quickly connected two wires to the machine. On a table he found a transformer. Thalia stood by in silence while he hooked up wires, condensers, and a small loading coil. Presently he looked up with a nod.
"We'll give her a try and see what happens."
"Stand over there in front of the helix," Standish said. "I don't think there's any danger. Unless I'm wrong, the thing simply places the patient in an electro magnetic field and transmits an alternating vibration to the human brain."
He played with the dials a long time, twisted a rheostat experimentally.
"Notice anything?"
"Yes, I ..." The Earth girl's voice died off. A vacant look entered her eyes. "What is your wish?" she asked suddenly.
Standish made a quick adjustment to the controls. "Sit down," he commanded.
Obediently, Thalia moved across to a chair and sat stiffly erect.
"You have studied some mathematics," Standish said then. "Tell me, what is the principal of the algebraic curve?"