“so you want me to tell you something about the dam?” said mr. whitney, smiling at his rodman. the two were sitting on the side of a hill overlooking the construction work several days after bob had been promoted from the office to the proud position of being the chief’s aide. he had been on a message to the cofferdam gang and had returned to find the boss seemingly loafing. when he saw there might be a few free moments before he was set to work again he ventured some questions regarding the thing that was of most interest to him.

the way mr. whitney answered was encouraging, so bob came back, “yes, sir, i’d like to know a lot more about it than i do. anything you tell me is going to help. i’ve picked up a little here and there and know some of the details but i don’t really know anything about the general plan. wasn’t there any irrigation on the rio grande before the reclamation service took hold?”

“indeed there was,” was the answer. “the indians were the first irrigators. the pueblo or village indians, as they were called, while it was in a crude way, irrigated all the land on which they raised corn. they were the first settlers of the rio grande valley. we know this is so, for one of the spanish conquistadores, coronado by name, wrote it down in the record of his travels. when he marched from the south into what is now new mexico in search of the gold which was the aim and hope of all the adventurers of his time, he found the indians irrigating the land by means of crude ditches dug with their primitive implements. this was the first record we have, but it has been established beyond any reasonable doubt that such irrigation as he found was practiced here by this river that flows below us long before columbus discovered america. the theory is that in all probability irrigation along the rio grande was in vogue even before the egyptians used the waters of the nile for the same purpose. when the first spanish settlers came along, and later the americans, they adopted the same methods of making the ground productive as had the indians. all we have done as time went on is to improve the general principles taken from the savages. of course, as we made better tools, we have been able to build larger ditches and so increase the area of fertile land far beyond the dreams of the indians.”

“but, mr. whitney,” bob put in, “if irrigation was such a success, why weren’t more canals constructed before the government took hold of the job?”

mr. whitney laughed. “the greatest drawback was a ridiculous thing. a long time ago a treaty was made with mexico which prohibited the storing of flood water on the rio grande and it’s the flood water that is used in modern irrigation.”

“but how would that hurt the mexicans?”

“the reason given was that the lack of water would interfere with navigation, but when you realize that it isn’t until the rio grande flows a thousand miles on the other side of the mexican boundary that any navigation begins, you can see how ridiculous that objection was. we were able to get this treaty broken at last and have substituted a new one in its place. under this new treaty we guarantee to deliver to mexico a certain minimum number of gallons of water a year and we are at liberty to do what we like with the remainder. by building this dam we will give mexico only one-tenth of the total amount stored each year, yet that one-tenth is more than half as much again as they are getting now!”

“that new treaty clears up the biggest trouble, then, doesn’t it?” said bob. “but in the early days of settlement i wouldn’t have thought that the mexicans would have enforced the old treaty.”

“i don’t suppose they could,” returned mr. whitney, “but the uncertainty kept many a prospective irrigator from spending his time or energy in the work. now, however, even mexico is strong for the completion of the big dam, as it will irrigate a lot of her land which before was desert. besides, it will cost them nothing and that always appeals to folks—including mexicans!”

“it certainly is going to be some big dam,” said bob, waving his hand over the work spread out below them. “how high is it going to be?”

“if i remember the figures exactly, it will be two hundred and twenty-five feet from the foundation to the top—almost as tall as the flatiron building in new york. it will be nearly twelve hundred feet from bank to bank across the top.”

“it will have to be awfully thick, won’t it, to be able to hold the water?”

“it’ll be twenty feet through at the top. at the bottom it has to be pretty nearly two hundred feet. although it is all filled in now by masonry, they had to dig down to bedrock and to get there they had to excavate about five hundred and fifty thousand cubic yards of sand, shale and rock. it’s sixty-five feet from the river bed to the bottom of the foundation.”

“that must’ve been some job. i wish we had been here to do it, don’t you, mr. whitney?”

the man smiled at the boy’s eagerness. “there will be other jobs for us to do,” he said, “where we’ll go through with it from the start to the finish. i wouldn’t be a bit surprised if about the time you have graduated from college we would be ready to begin work on the labyrinth which you and jerry found. you’ll come out to be my chief assistant and we’ll do the whole thing.”

“that’ll be great,” said bob, his face glowing. “but go ahead about this dam. i’m learning more than i have all the time i’ve been here poking around by myself. it ought to make a pretty big lake when once the water is dammed up, shouldn’t it?”

“you bet,” said mr. whitney. “the lake will be forty miles long, and if you started to walk around it, keeping directly on the shore line, you would have covered two hundred miles before you could get to your starting point. if the water it will hold was spread out one foot deep, it would cover nearly five thousand miles or about twice the size of the state of delaware.”

“and how many gallons will it hold?”

“there will be so many that we have found it easier to figure in what we call acre feet. the gallon figures are too cumbersome. an acre foot is the amount of water that would be sufficient to cover an acre one foot deep.”

“and the water of the reservoir would cover how many acres?”

“two million at least,” he answered. “in gallons that would be something around nine-hundred billion gallons. so you can see how much easier it is to figure in acre feet.”

“i should say so,” said bob. “but it must cost a fortune to construct all this. do you know about how much?”

“the estimate for the dam itself is five million, three hundred thousand dollars, and the canals and other expenses will bring the entire cost up to over seven million.”

“gee, how will the farmers ever pay that off? didn’t you tell me that the money was only advanced by the government and that the farmers would have to return it after the water is delivered to them?”

“i did,” said mr. whitney, “but as the dam will furnish enough water to irrigate one hundred and eighty thousand acres, you see that brings the cost down to about forty dollars an acre, which won’t be much once it is all under cultivation. this charge is like a mortgage—the government is secured by the land itself. but it won’t be long now—two or three years at the outside—before the dam is finished and the land is ready to be cultivated. ted adams, my predecessor here, finished up a diversion dam below at leesburg which has been a help.”

“what a wonderful thing it is,” bob said at last.

“yes,” he said, “it is wonderful. centuries of primitive irrigation have furnished the knowledge which has made this dam possible. it is the greatest irrigation scheme ever attempted and i am proud that it is to be my lot to finish it—mighty proud.” his eyes were on the swarming crowd of men, the cable wires humming, the derricks shifting their burdens, all the myriad activities that went to the building of his dam. “it will be a dream fulfilled,” he said almost to himself. then, suddenly, he knocked the ashes from his pipe and got up. “come, bob,” he said. “we must get on the job. we’re not bringing the finish along any quicker by sitting here dreaming of it.”