"Well, Cyrus," asked the reporter, "if Lincoln Island is not more than two or three thousand miles from New Zealand or Chile?""Well," replied the engineer, "instead of building a house we will build a boat, and Master Pencroft shall be put in command--""Well then," cried the sailor, "I am quite ready to be captain--as soon as you can make a craft that's able to keep at sea!""We shall do it, if it is necessary," replied Cyrus Harding.
But while these men, who really hesitated at nothing, were talking, the hour approached at which the observation was to be made.What Cyrus Harding was to do to ascertain the passage of the sun at the meridian of the island, without an instrument of any sort, Herbert could not guess.
The observers were then about six miles from the Chimneys, not far from that part of the downs in which the engineer had been found after his enigmatical preservation.They halted at this place and prepared for breakfast, for it was half-past eleven.Herbert went for some fresh water from a stream which ran near, and brought it back in a jug, which Neb had provided.
During these preparations Harding arranged everything for his astronomical observation.He chose a clear place on the shore, which the ebbing tide had left perfectly level.This bed of fine sand was as smooth as ice, not a grain out of place.It was of little importance whether it was horizontal or not, and it did not matter much whether the stick six feet high, which was planted there, rose perpendicularly.On the contrary, the engineer inclined it towards the south, that is to say, in the direction of the coast opposite to the sun, for it must not be forgotten that the settlers in Lincoln Island, as the island was situated in the Southern Hemisphere, saw the radiant planet describe its diurnal arc above the northern, and not above the southern horizon.
Herbert now understood how the engineer was going to proceed to ascertain the culmination of the sun, that is to say its passing the meridian of the island or, in other words, determine due south.It was by means of the shadow cast on the sand by the stick, a way which, for want of an instrument, would give him a suitable approach to the result which he wished to obtain.
In fact, the moment when this shadow would reach its minimum of length would be exactly twelve o'clock, and it would be enough to watch the extremity of the shadow, so as to ascertain the instant when, alter having successively diminished, it began to lengthen.By inclining his stick to the side opposite to the sun, Cyrus Harding made the shadow longer, and consequently its modifications would be more easily ascertained.In fact, the longer the needle of a dial is, the more easily can the movement of its point be followed.The shadow of the stick was nothing but the needle of a dial.The moment had come, and Cyrus Harding 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 midday 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 an hour.
Fifteen degrees multiplied by five hours give seventy-five degrees.
Then, since Washington is 770? 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 thirty-seventh parallel, and between the hundred and fiftieth and the hundred and fifty-fifth meridian to the west of the meridian of Greenwich.
The possible fault which he attributed to errors in the observation was, it may be seen, of five degrees on both sides, which, at sixty miles to a degree, would give an error of three hundred miles in latitude and longitude for the exact position.
But this error would not influence the determination which it was necessary to take.It was very evident that Lincoln Island was at such a distance from every country or island that it would be too hazardous to attempt to reach one in a frail boat.
In fact, this calculation placed it at least twelve hundred miles from Tahiti and the islands of the archipelago of the Pomoutous, more than eighteen hundred miles from New Zealand, and more than four thousand five hundred miles from the American coast!
And when Cyrus Harding consulted his memory, he could not remember in any way that such an island occupied, in that part of the Pacific, the situation assigned to Lincoln Island.
