To what height this feeling might have attained it is impossible to say, for just as they had arrived at the electric furnace a sudden tap on the door interrupted their proceedings.
With an impatient click of his tongue the aged scientist glanced sharply round in the direction of the sound.
"Now who the devil's that?" he exclaimed. "I have given orders repeatedly that when I'm in here I am not to be disturbed."
He shuffled wrathfully down the room, and, jerking open the door, revealed the lean figure of Mrs. Ramsay.
"What's the matter?" he demanded. "Why don't you obey my instructions?"
"It's no good getting cross," returned the housekeeper impassively. "You asked Mr. Medwin to call, and you can't leave 'im sitting in the study."
"Oh, he's come, has he?" was the slightly mollified answer. "Well, in that case I suppose we had better go along and make ourselves civil to him." He turned to Colin, who had followed him to the door. "You will stay to tea, of course?" he added.
Colin, who was trying hard not to smile, expressed his willingness, and, having closed and locked the laboratory, the Professor conducted him back through the hall to the room which they had recently quitted.
A big, clean-shaven, middle-aged man, who was standing in front of the fire, stepped forward at their entrance.
"I hope I am not too punctual," he began, in a curiously smooth voice. "I think four o'clock was the time you mentioned in your letter."