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peals of almost unceasing laughter. For tle fellow altogether away from a they understood the reason before I did. motherly protection. He had come withDo you?
in a certain distance, beyond which he "No? Well, the explanation is as sim- could not pass. My companions called ple as all the others have been, and fol- me back, as they wanted to make some lows a well-known natural law. The calculations, and I sprang back as easily gravitation of the little planet was almost as I had jumped across. as much less than that of the earth as “By looking at the earth, they had disits size, and I weighed—had scales been covered that we were traveling around
provided-about ten pounds, more or less. With my muscles, it was nothing to jump seventy or eighty feet, the difficulty being to keep on the ground at all.
"Now, I suppose you are wondering how it was that the planet was not drawn to the earth by the great attraction of the latter body. It took the scientists less than five minutes to determine the reason accurately. It was because of the composition of Nebula, such ingredients having been put together in its formation as to repel the advances of the earth toward a union, but not enough to drive the lit
that planet from east to west, while it turned over from west to east. The combined motions in opposite directions made our speed about two thousand miles an hour, so that we should circle the earth every twelve hours. This calculation was of the greatest importance, since we would have to time our departure accurately in order to land where we wanted to. If we allowed our balloon to ascend at the wrong time, it was just as likely that we should find ourselves over an ocean as over the land, and just as likely over Africa as over America. Figures were jotted down, and we then the details of the stay on Nebula. Let determined upon an exploration of our it suffice to say that we had to wait there kingdom.
twelve hours for the United States to get "At this point I did some figuring my back to us. In the meantime food was self. It seemed reasonable to me to sup- cooked and served. Then, when Calipose that, if I could jump seventy feet fornia was just rounding the edge of the with little effort, I could run just so many earth from the west, we lifted anchor and times faster here than I could on the started our motor, bidding but a temearth. And I proved it. I pointed out porary farewell to our little world, for to the others a clump of trees about a we all fully determined that this should mile away, and then, asking them to time not be our only trip there. The journey me, started. My work surprised me be- back was the reverse of the conditions yond expectations, for I leaped into the in coming away from home; and by opair about thirty feet at each bound, · erating the powerful machinery,.we were alighted easily some sixty feet beyond, enabled to make our landing within a and took another bound, as simply as if very short distance of the spot we had on the earth, yet with an ease that gave left but little more than half a day before. me not the slightest weariness. I ran But it was moonlight, and the night was back and found that I had made the two beautiful in the mountains. We camped miles in a fraction under three minutes! where we landed, and came down to the
“'At that rate,' said I, I can run ranch next morning.” around this ball at the rate of forty-five He stopped abruptly and relighted his miles an hour; and if your calculations pipe. I waited for him to continue. are correct, and it is eight miles in di “What do you think of it?” he asked. ameter, it must be about twenty-five miles “I think it the most remarkable tale I in circumference. I can, therefore, if I ever heard," I replied. don't get winded, circle it in less than “And perhaps you would like a look at forty minutes, and I'm going to do it. our little world ?” he asked.
"Two of the party volunteered to ac- I was instantly alert, and rose quickly company me, and off we started at a' from my chair. good clip, the stop watches being out at “Come along, then,” he said, leading the word 'Go!' None of us seemed to the way. mind the exertion, if floating lightly in Into the garret we went, where he dug the air can be called exertion; and we ran out of a corner a fine hand telescope, along through the forests and across the which he carried to the dormer window plains with the ease and grace of grey on the east side. Swinging it into a posihounds. For half an hour we did not tion with its disc pointed at an angle of slacken our pace; but there ap- about 60 degrees, he peered carefully into peared before us a deep gulley, at it, then adjusted it again, screwed it the bottom of which was a stream. tightly onto a swivel, and bade me take Here we came to a standstill. The a careful look. I was more than amazed, gulch was quite fifty feet deep and for before me in the heavens was a globe nearly a hundred wide at the top; and as of dim light, upon which I could. with far as we could see, there was no better care, trace the outlines of what seemed crossing in sight. Elated at our work, to be land and water. For but a moment and feeling certain we could make the I looked, and then he took the instrument leap, we all ran at it together. Every away from me and turned it from the litbound we took was better than the pre- tle planet. vious one; and when we reached the edge "Now find it,” he commanded. of the arroya, we sprang into the air like I tried with all my might to locate it, birds and landed on the opposite side but nothing revealed itself save the stars fully ten feet beyond the edge. After and the moon. this the going was simple, and we made “That's the reason it has never been the trip safely, having circumambulated discovered,” he said; "because astronothe globe in thirty-seven minutes. mers have always been looking for things
"I am not going to tire you with all farther away, ever forgetting the fact
Here the water is so shoal as to require wading. One man pulls the boat up; the plane-table man has the tripod. with protected "movement" and plane table itself in its case; and the third man has the sheet in its
waterproof case, in his hand. Launch in the distance.
Making Charts from Nature's Model-Coastwise Surveys Essential to
Navigation and Commerce
Formerly Editor, The American Inventor
F the average man be asked how the for the work of the Coast and Geodetic ships of our commercial fleets find Survey, our navies, both commercial and their way about the coasts and rivers war, would be in a very helpless condi
and lakes of the United States, he tion in regard to navigation of the coasts will be apt to tell you that he supposes and rivers. For while a knowledge of they use "maps" and navigation instru- navigation, a few tables, and an instruments. Pressed as to his knowledge of ment or two will take a ship anywhere the origin of these “maps," he may in- about the ocean, a chart showing coast form you that they are made by firms lines and depth of water is absolutely eswho sell them, or he may say that he sential for navigation near land. guesses the Government makes them. Asked as to how they are made, he will
U. S. Coast and Geodetic Survey probably "give it up.” It is a strange Now, this chart making is a big subthing, when you come to think of it, that ject. The Coast and Geodetic Survey, so important a branch of commercially located in Washington, occupies two important scientific work as the making large buildings; has a very complete of charts of the coasts and the bodies of plant for the printing of the charts and water of this country, should be so little the engraving of the plates, and, besides known and understood. If it were not these departments, equips and sends out many parties each year for making the actual surveys which become charts after a while. This story deals with the work of the plane-table parties, who come after the triangulation parties, and who actually make the plane-table sheets in the field, from nature as a model, from which the topographic details of the charts are obtained.
In the first place, it should be explained that before a plane-table party goes to work, a triangulation party must previously have been over the ground,
or level. The plane table, as used in the survey, consists of a heavy tripod, on top of which is what is called the movement, a device now made of aluminum and brass, to which is attached the table proper. It allows the table to be leveled accurately by means of leveling screws, and revolves in a complete circle, besides providing a tangent screw movement to move the table in a small arc, very slowly.
With the plane table, is used a surveying instrument called an alidade. This
and have determined with great accuracy consists of a small telescope, mounted like the exact location of certain points. Some a transit, so that its only movement is in of these points are covered with wooden a vertical arc. The standard of the structures called signals. Sometimes a telescope ends in a metal base which triangulation point may be a church is long and narrow, the sides of which spire, a tall tree, or other landmark. It are absolutely straight and parallel, makes no difference how long a time and accurately in line with the line elapses between triangulation and plane of vision of the telescope. The telescope table surveying, provided the prede- is further provided with an eyepiece in termined triangulation points are still vis- which are cross-hairs whose distance ible, or, if destroyed, recoverable. A apart bears a certain definite, arbitrary revery large part of this country has been lation to the focal length of the objective triangulated—all the coast-line and most and the divisions painted on a long piece of the important rivers and lakes.
of wood, called a telemeter rod. These
divisions, and the distances between the What is a Plane Table ?
cross-hairs, are so adjusted that when the A plane table is exactly what its name rod, held in an upright position, is viewed implies—a table which can be made plane through the telescope, the number of di