Page:Works of Jules Verne - Parke - Vol 5.djvu/425

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A PROBLEM IN TRIANGLES
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knelt on the sand, and with little wooden pegs, which he stuck into the sand, he began to mark the successive diminutions of the stick's shadow. His companions, bending over him, watched the operation with extreme interest. The reporter held his chronometer in his hand, ready to tell the hour which it marked when the shadow would be at its shortest. Moreover, as Cyrus Harding was working on the 16th of April, the day on which the true and the average time are identical, the hour given by Gideon Spilett would be the true hour then at Washington, which would simplify the calculation. Meanwhile as the sun slowly advanced, the shadow slowly diminished, and when it appeared to Cyrus Harding that it was beginning to increase, he asked, "What o'clock is it?"

"One minute past five," replied Gideon Spilett directly. They had now only to calculate the operation. Nothing could be easier. It could be seen that there existed, in round numbers, a difference of five hours between the meridian of Washington and that of Lincoln Island, that is to say, it was mid-day in Lincoln Island when it was already five o'clock in the evening in Washington. Now the sun, in its apparent movement round the earth, traverses one degree in four minutes, or fifteen degrees one hour. Fifteen degrees multiplied by five hours give seventy-five degrees.

Then, since Washington is 77° 3′ 11″, as much as to say seventy-seven degrees counted from the meridian of Greenwich—which the Americans take for their starting-point for longitudes concurrently with the English—it followed that the island must be situated seventy-seven and seventy-five degrees west of the meridian of Greenwich, that is to say, on the hundred and fifty-second degree of west longitude.

Cyrus Harding announced this result to his companions, and taking into consideration errors of observation, as he had done for the latitude, he believed he could positively affirm that the position of Lincoln Island was between the thirty-fifth and the fortieth parallel, and between the hundred and fiftieth and the hundred and fifty-fifth meridian observation was, it may be seen, of five degrees on both

The possible fault which he attributed to errors in the sides, which, at sixty miles to a degree, would give an error