"Apropos of getting lost, Roberts," said the older man, "we had a little experience with the lad here that is worth repeating," and beginning from the snipe-hunt, he related the entire affair, showing first how well they had got the laugh on the tenderfoot, and how he had got back in return. Roberts laughed long and heartily at the picture conjured up of Roger sitting in the boughs above the party, hearing them discuss plans for his rescue and heroically resolving to leave nothing undone till they should find him. [Illustration: DIFFICULTIES OF WORK. In the Giant Tule Swamps in the Southern Sacramento Valley. The umbrella is not for comfort, but to keep the sun off the instrument. _Photographs by U.S.G.S._] "I didn't fare as well when I got trapped down there," he commented, "and while I suppose it was funny, I couldn't see the joke of it myself." "Was that in the tule grass?" asked Field. "Tell us the yarn." "I think I told you," began the new assistant, "how hard that stuff is to make a way through, and though it is really almost as tangled as this marsh work up here, the ground is so flat that far fewer bench marks are required. We had taken a long sight, because there was a sort of depression at that point which we wanted to delimit, and I was quite a distance from the plane table. Suddenly I felt a swish of water at my feet, my first realization that the tide was coming in. This had often happened before, and the water usually rose to a little above the knee, when, as soon as the tide ebbed, it would flow out and leave all dry again. "Of course I was aware that I was working in a slight depression, but as a matter of fact it never occurred to me that this would make any especial difference. I was surprised, certainly, at the strength of the tide as it flowed in, and I remember a little later wondering whether it was spring tide and not being able to find any reason for the heavy flow, but it was only casually that the matter occurred to me at all. Few minutes elapsed, however, before I realized that any greater increase of depth would be a really serious matter. The water was already above my knees and increasing at an alarming rate. I think I have shown you how hard it is to get through that stuff, and to cross a hundred yards of tule grass is a matter of half an hour's work. Still, at any moment, I thought the water would reach its maximum and I felt ashamed to start back after all the labor of reaching the point where I then was.