When he had gone Vance got up with alacrity, and bent over the scrap of paper on Markham’s desk.
“My word!” He took out his monocle and studied the symbols for several moments. “Most allurin’. Now where have I seen that formula recently? . . . Ah! The Riemann-Christoffel tensor—of course! Drukker uses it in his book for determining the Gaussian curvature of spherical and homaloidal space. . . . But what was Sprigg doing with it? The formula is considerably beyond the college curricula. . . .” He held the paper up to the light. “It’s the same stock as that on which the Bishop notes are written. And you probably observed that the typing is also similar.”
Heath had stepped forward, and now scrutinized the paper.
“It’s the same, all right.” The fact seemed to nonplus him. “That’s a link anyway between the two crimes.”
Vance’s eyes took on a puzzled look.
“A link—yes. But the presence of the formula under Sprigg’s body appears as irrational as the murder itself. . . .”
Markham moved uneasily.
“You say it is a formula that Drukker uses in his book?”
“Yes. But the fact doesn’t necessarily involve him. The tensor is known to all advanced mathematicians. It is one of the technical expressions used in non-Euclidean geometry; and though it was discovered by Riemann in connection with a concrete problem in physics,[16] it has now become of widespread importance in the mathematics of relativity. It’s highly scientific in the abstract sense, and can have no direct bearing on Sprigg’s murder.” He sat down again. “Arnesson will be delighted with the find. He may be able to work out some astonishing conclusion from it.”
“I see no reason,” protested Markham, “to inform Arnesson of this new case. My idea would be to keep it under cover as much as possible.”