Trenholm stared at her. “Grave,” he repeated, then, suppressing comment, went ahead decoding the message. “This center one appears the simplest,” he said. “Here the perforations cut are numbers 5, 12, 20, 5, 18, 20—odd letters, E, L, T; even letters, E, R, T. Got them down, Miss Ward?”
“They make the word—letter,” briefly, not glancing up. “Go ahead.”
“The next letters are E, I, T, for the odd, and E, H, N, R, for the even.” Trenholm laid down his perforation gauge and frowned. “The code seems to fail here,” he grumbled. “It has given four even letters and only three odd. The other way around would be all right, but it is impossible to make a word with more even than odd letters.”
“Let me see the envelope.” Miriam put aside her pencil and carefully examined the stamps against the light. “Look, Mr. Trenholm, here are pinholes opposite some of the letters—two opposite the odd T, and one opposite the even H.”
“Probably they stand for repetitions of the same letters, in which case the letters would be: odd—E, I, T, T, T; even—E, H, H, N, R,” declared Trenholm. “But they don’t make sense.” He paused and looked at the stamps already decoded. “See here, the first letter in each word we have deciphered is on the side of the stamp which faces the left side of the envelope.”
“Oh, then that accounts for the apparently careless manner in which the stamps are stuck on the envelope,” said Miriam. “The only letter on the second stamp, which is indicated by a cut in the way you have just described, is T.”
“So our next word begins with T.” Trenholm took up a pencil and did some figuring on Miriam’s pad. “With so many T’s and H’s to use, suppose we start off with Th,” he began, “and the next letter is either E, I, or T. It must be one of the vowels. No, E is no good.” Trenholm ran his fingers through his hair until it stood upright. “We’ll take I, and here is an R available—by Jove—thirteenth!”
“So it is!” Miriam’s excitement was rising. “The words we have so far are, ‘watch thirteenth letter——grave.’”
“Now for the last stamp!” Trenholm took up gauge and pencil. “The odd letters are E, two I’s, one indicated by another pinhole, and S. The even letters are C, D, S, U. The position of the stamp shows that the first letter is S. Of the four even letters available for the next position, only the vowel can be used, making Su.” Trenholm paused and wrote rapidly several combinations of the available letters, then looked up with a low exclamation—“Suicides.”
“And the completed message then stands—‘Watch thirteenth letter suicides grave,’” repeated Miriam. “What do you make of it, Mr. Trenholm?”