Total of each vertical, horizontal, and diagonal line = 65.
Now came the crucial test of constructing a square with the same number of subdivisions as there were on Humphrey's cipher, and an intelligent application of the figures to the symbols of latitude and longitude; but here I was nonplussed, for I had no copy of the cipher, neither could I remember the actual numbers of subdivisions.
Just then, however, my father and uncle returned, and while at supper they did not fail to notice my excitement.
"Whatever is the matter with you, Reggie?" asked Uncle Herbert. "You look like a cat on hot bricks."
I was burning with impatience to let them know of my evening's work and its results, but, fearing that after all there might be some flaw in my theory, and having another motive in view, I managed to restrain myself.
Little more was said during the meal, but on its completion preparations were made to continue the investigations of the mystery.
"I say, pater," I exclaimed. "Don't you think it would be better to make a copy of the cipher: it would save the original, you know."
"Just so, Reggie, I will; but I think it's about time you went to bed."
"Another hour won't make much difference," I replied. "You see, to-morrow's a holiday."
My father assented, and gleefully I set about the task of making a duplicate of the cipher, of which I was now firmly convinced I held the key.