A PRACTICAL USE OF TRIGONOMETRY.
It was Binney Gibbs who had come up the river from Fort Yuma several days before, with General Elting, to meet the second division, and guide them to "The Needles," the point at which the line was to cross the Colorado. The other divisions, which had followed the Gila route, and crossed the Colorado at Fort Yuma, where the desert was narrower, had reached the Pacific ere this, and gone on to San Francisco. The hardest task of all, that of running a line over the desert where it was two hundred and fifty miles wide, had been reserved for Mr. Hobart's men, who had proved themselves so capable of enduring and overcoming hardships.
Binney had waited impatiently in camp until the transit-party reached it, expecting to see Glen ride in at its head with the front flag. Then he had borrowed a horse, and set forth to find the boy whom he had once considered his rival, but whom he now regarded as one of his best friends.
After the first exchange of greetings, they stood and looked at each other curiously. Glen's hair hung on his shoulders, and the braid that bound the brim of his sombrero was worn to a picturesque fringe, matching that of his buckskin shirt. He was broader and browner than ever; and though his face was still smooth and boyish, these last three months had stamped it with a look of resolute energy that Binney noticed at once.
He, too, was brown, though not nearly so tanned as Glen, in spite of the burning suns of the Gila Valley; for his work had kept him under cover as much as Glen's had kept him in the open air. As General Elting's secretary, Binney had spent most of his time in the ambulance, that, fitted up with writing-desk and table, was the chief-engineer's field-office, or in temporary offices established in tents or houses wherever they had halted for more than a day at a time. He had evidently met with barbers along the comparatively well-travelled Gila; while, as compared with Glen's picturesquely ragged costume, his was that of respectable civilization. Although he, too, was the picture of health, his frame lacked the breadth and fulness of Glen's, and it was evident at a glance that, in the matter of physical strength, he was even more greatly the other's inferior than when they left Brimfield.
Glen could not help noting this with a feeling of secret satisfaction; but, as they rode towards camp together, and Binney described his winter's experiences, Glen began to regard him with vastly increased respect. He thought he had studied hard, and done well to master the mysteries of adjusting and running a level, perfecting himself as a rodman, and learning to plot profile; but his knowledge appeared insignificant as compared with that which Binney had picked up and stored away. Not only had he learned to speak Spanish fluently, but he had become enough of a geologist to talk understandingly of coal-seams and ore-beds. He had the whole history of the country through which he had passed, from the date of its Spanish discovery, at his tongue's end. He spoke familiarly of the notable men to whom, at General Elting's dictation, he had written letters, and altogether he appeared to be a self-possessed, well-informed young man of the world.
Poor Glen was beginning to feel very boyish and quite abashed in the presence of so much wisdom, and to wonder if he had not been wasting his opportunities on this trip as he had those of school. His thoughts were inclining towards a decidedly unpleasant turn, when they were suddenly set right again by Binney, who exclaimed, "But, I say, old man, what a fine thing you fellows have done this winter! The general declares that you have made one of the most notable surveys on record; and it's a thing every one of you ought to be proud of. You should have heard him congratulate Mr. Hobart. He asked at once about you, too, and wants to see you as soon as you get in. He seems to take a great interest in you, and has spoken of you several times. I expect, if you choose to keep on in this business, you can always be sure of a job through him. He seems to think it queer that you should be a year older than I am; but I told him it was certainly so, because I knew just when your birthday came."
Glen was on the point of saying that, if Binney knew that, it was more than he did, but something thing kept him silent. He hated to acknowledge that he knew nothing of his real birthday, nor how old he really was, but he wondered if he could truly be a year older than this wise young secretary.
At this point the conversation was interrupted by their arrival at camp, and by General Elting stepping from his tent to give Glen a hearty handshake as he exclaimed,
"My dear boy, I am delighted and thankful to see you again. I tried to persuade our friend Mr. Hobart, when I last saw him at Santa Fé, that, in spite of your performance on that railroad ride you and I took together last summer, you were too young to make the trip I had laid out for him. He said he didn't know anything about your age, but that you were certainly strong and plucky enough for the trip. I made him promise, though, to try and induce you to go back from Isletta; but he doesn't seem to have succeeded."
"No, sir," laughed Glen, "and I'm awfully glad he didn't, for it's been the most glorious kind of a trip, and I have enjoyed every minute of it."
"I am glad, too, now that it is all over; but I must tell you that, if I had not been assured that you were a whole year older than my young secretary here, I should have insisted on your going back, for I considered it too hard and dangerous a trip for a boy so young as I had supposed you to be until then."
Here was another good reason why Glen was glad he had remained silent on the subject of his birthday.
"Now what do you think of running a line across the desert ahead of us?" continued the chief-engineer; "are you as anxious to undertake that as you were to cross Arizona?"
"Yes, indeed, I am, sir," replied Glen, earnestly. "I am anxious to go wherever the second division goes; and if anybody can get a line across that desert, I know we can."
"I believe you can," said the chief, smiling at the boy's enthusiasm, "and I am going along to see how you do it."
The Colorado was so broad, deep, and swift that Glen wondered how they were going to measure across it, and had a vague idea that it could be done by stretching a long rope from bank to bank. He asked "Billy" Brackett; and when the leveller answered, "By triangulation, of course," Glen showed, by his puzzled expression, that he was as much in the dark as ever.
"You have studied geometry and trigonometry, haven't you?" asked the leveller.
Glen was obliged to confess that, as he had not been able to see the use of those studies, he had not paid much attention to them.
"Well, then, perhaps you'll have a better opinion of old Euclid when you see the practical use we'll put him to to-morrow," laughed "Billy" Brackett.
Glen did see, the next day, and wondered at the simplicity of the operation. The front flag was sent across the river in a boat, and on the opposite side he drove a stake. While he was thus engaged, a line a quarter of a mile long was measured on the bank where the rest of the party still remained, and a stake was driven at each end of it. The transit was set up over one of these stakes, and its telescope was pointed first at the other and then at the one across the river, by which means the angle where it stood was taken. It was then set over the stake at the other end of the measured line, and that angle was also taken. Then Mr. Hobart drew, on a leaf of his transit-book, a triangle, of which the base represented the line measured between the two stakes on his side of the river, and one side represented the distance across the river that he wished to find. He thus had one side and two angles of a triangle given to find one of the other two sides, and he solved the problem as easily as any boy or girl of the trigonometry-class can whose time in school has not been wasted as Glen Eddy's was.
It was a simple operation, and one easily performed, but it involved a knowledge of the four fundamental rules of arithmetic, of proportion, or the rule of three, of geometry, of trigonometry, and of how to use a surveyor's transit; all of which, except the last, are included in the regular course of studies of every boy and girl in America who receives a common-school education.
Glen had also been sent across the river, where he held his rod so high up on the bank that the cross hair in the telescope of the level cut just one tenth of an inch above its bottom. Then, when "Billy" Brackett came over, and went on beyond Glen, he set the level up so high on the bank that, through it, he could just see the top of the rod, extended to its extreme length. So they climbed slowly up out of the Colorado Valley, and began to traverse the dreary country that lay between it and the Sierra Nevada.
For the first hundred miles or so they got along very well, so far as water was concerned, though the mules and horses speedily began to grow thin and weak for want of food. The patches of grass were very few and far between, and the rations of corn exceedingly small; for in that country corn was worth its weight in gold, and scarce at that.