"Because," exclaimed the professor, "the papers have been written on with invisible fluid of some kind. Their exposure to the warm rays of the sun has brought out the writing."
"It's getting clearer," said Ralph, eagerly perusing the sheet he held. "I can't quite make it out yet, though."
He exposed the sheet he held to the sunlight, while Walt Phelps leaned interestedly over his shoulder.
"Why-why," the boy stuttered, "it's something about this church. Look here, I can see the 'Church of St. Gabriel, the old mission,' as plain as anything, and-and, why, professor," shouted the boy, half wild with excitement, "I believe that this paper, by some wonderful chance, may be the means of getting us out of here."
"Let me see," demanded the professor, taking the paper from the boy's trembling hands. Sure enough, it was covered with characters written closely, and seemingly hastily.
"'This record, made the seventeenth day of August, 1909,'" he read out, "'is to be kept in case of accidents. The secret passage lies four squares from the fifth square from the last window on the right hand side toward the altar. The old altar rail pulls back, exposing the trapdoor. Treasure in passage, one hundred paces from north of tunnel in wall, to right.' Give me that other page, Ralph, quick!"
The professor's voice shook strangely, and his dim eyes shone behind his spectacles. Rapidly he warmed the page Ralph handed him in the sunlight, and more writing leaped into view.
"'Written by me with onion juice on above date. Jim Hicks, prospector, formerly of Preston Hollow, N. Y. State. This to be an instrument for my heirs, if any, and if this is ever found.' And here is something that seems to be a postscript," gasped the professor, amazedly.
"'Will have to leave this in church and trust to luck. Place not deserted as I had thought, but in possession of Mexicans. If chance should bring this to an American's notice, let them search out Jim Hicks, the prospector, rightful owner of treasure by right of discovery, and legacy of Don Manuel Serro y Fornero, the last descendant of the old monk, Brother Hilarito.'"
"Good gracious, does that mean this church?" breathed Walt Phelps, his eyes as round as two marbles.