"A note for P.B. is on the table," was the laconic message: on reading which I inserted my key, swung the heavy door outward, and opened the lighter inner door. The note was lying on the table and I brought it out to the landing to read by the light of the staircase lamp.
"Apologise to our friends," it ran, "for the slight change of programme. Norbury is anxious that I should get my experiments over before the Director returns, so as to save discussion. He has asked me to begin to-night and says he will see Mr. and Miss Bellingham here, at the Museum. Please bring them along at once. The hall porters are instructed to admit you and bring you to us. I think some matters of importance may transpire at the interview.—J.E.T."
"I hope you don't mind," I said apologetically, when I had read the note to Ruth.
"Of course I don't," she replied. "I am rather pleased. We have so many associations with the dear old Museum, haven't we?" She looked at me for a moment with a strange and touching wistfulness and then turned to descend the stone stairs.
At the Temple gate, I hailed a hansom and we were soon speeding westward and north to the soft tinkle of the horse's bell.
"What are these experiments that Doctor Thorndyke refers to?" she asked presently.
"I can only answer you rather vaguely," I replied. "Their object, I believe, is to ascertain whether the penetrability of organic substances by the X-rays becomes altered by age; whether, for instance, an ancient block of wood is more or less transparent to the rays than a new block of the same size."
"And of what use would the knowledge be, if it were obtained?"
"I can't say. Experiments are made to obtain knowledge without regard to its utility. The use appears when the knowledge has been acquired. But in this case, if it should be possible to determine the age of any organic substance by its reaction to X-rays, the discovery might be of some value in legal practice—as in demonstrating a new seal on an old document, for instance. But I don't know whether Thorndyke has anything definite in view; I only know that the preparations have been on a most portentous scale."