"Most of them. You see, suppose in the middle of summer a river is ten feet deep with a three-mile current, in the autumn is only four feet deep with a two-mile current, but in the spring floods goes rushing through its bed forty feet deep with a ten-mile current, it makes a mighty difference to the towns and villages all the way along. The destructiveness of a flood lies in the top few feet of water. In the second place, the navigation of a stream can only be estimated by its lowest depth recorded, and its horse power in the same way. But this same river, which in the autumn was only four feet deep and developed a corresponding horse power, would have an average depth of eight feet with four times the horse power. If then, the water that wastefully and ruinously flows down in the spring is conserved all through the summer, the river has been made more than four times as valuable."
"And how is this done?"
"That's too big a subject to take up now. Still, you can understand that if you dam the stream high up, and divert all the water over a certain height into immense reservoirs, the water could be let down gradually later. But that all depends on the measurement, which is taken daily for years, often—as in the case I was in—from a cable stretched from bank to bank, from which a little 'bos'un's chair' is hanging on a pulley, so that sitting in this little framework you can reach up to the cable and pull yourself to and fro. The one over the Susquehanna, where I was, is over a mile long, and of course it's pretty high up to allow for the sag, which is not small on a wire of that immense span."
Roger had a host of questions to ask but kept silent, not wanting to monopolize the talk when older men were there.
"By the way, Roberts," asked Field, seeking to change the subject from a topic which was stale to all the members of the party except Roger, "how did you like the work in the lower Sacramento Valley?"
"Parts of it weren't so bad, Mr. Field," was the reply. "Indeed, I think I've struck worse going right up here and in the Mud Lake district, but the project down there is on so large a scale that one is bound to become enthusiastic in the work. The bush is very dense, of course, semi-tropical in character, but where the growth is heavy the swamp is not so bad, so that it becomes a mere question of bushwhacking. Then, too, that southern stuff is all soft to cut and much easier to get through. The tule grass, however, is different."
"I've never been down in that tule grass," said one of the party, "is it as bad as has been described?"
"It's never been adequately described on paper," was the ready answer. "Uncle Sam wouldn't let the report go through the mails."
Roger grinned.
"But what is it like, Mr. Roberts?" he said.