The Mysterious Island
other to Alpha, and the space between the two legs gave him the angular
distance which separated Alpha from the horizon. In order to fix the
angle obtained, he fastened with thorns the two pieces of wood on a
third placed transversely, so that their separation should be properly
maintained.
That done, there was only the angle to calculate by bringing back the
observation to the level of the sea, taking into consideration the
depression of the horizon, which would necessitate measuring the height
of the cliff. The value of this angle would give the height of Alpha,
and consequently that of the pole above the horizon, that is to say, the
latitude of the island, since the latitude of a point of the globe is
always equal to the height of the pole above the horizon of this point.
The calculations were left for the next day, and at ten o’clock every
one was sleeping soundly.
Chapter 14
The next day, the 16th of April, and Easter Sunday, the settlers issued
from the Chimneys at daybreak, and proceeded to wash their linen. The
engineer intended to manufacture soap as soon as he could procure the
necessary materials--soda or potash, fat or oil. The important question
of renewing their wardrobe would be treated of in the proper time and
place. At any rate their clothes would last at least six months longer,
for they were strong, and could resist the wear of manual labor. But
all would depend on the situation of the island with regard to inhabited
land. This would be settled to-day if the weather permitted.
The sun rising above a clear horizon, announced a magnificent day, one
of those beautiful autumn days which are like the last farewells of the
warm season.
It was now necessary to complete the observations of the evening before
by measuring the height of the cliff above the level of the sea.
“Shall you not need an instrument similar to the one which you used
yesterday?” said Herbert to the engineer.
“No, my boy,” replied the latter, “we are going to proceed differently,
but in as precise a way.”
Herbert, wishing to learn everything he could, followed the engineer to
the beach. Pencroft, Neb, and the reporter remained behind and occupied
themselves in different ways.
Cyrus Harding had provided himself with a straight stick, twelve feet
long, which he had measured as exactly as possible by comparing it with
his own height, which he knew to a hair. Herbert carried a plumb-line
which Harding had given him, that is to say, a simple stone fastened
to the end of a flexible fiber. Having reached a spot about twenty feet
from the edge of the beach, and nearly five hundred feet from the cliff,
which rose perpendicularly, Harding thrust the pole two feet into
the sand, and wedging it up carefully, he managed, by means of the
plumb-line, to erect it perpendicularly with the plane of the horizon.
That done, he retired the necessary distance, when, lying on the sand,
his eye glanced at the same time at the top of the pole and the crest of
the cliff. He carefully marked the place with a little stick.
Then addressing Herbert--“Do you know the first principles of geometry?”
he asked.
“Slightly, captain,” replied Herbert, who did not wish to put himself
forward.
“You remember what are the properties of two similar triangles?”
“Yes,” replied Herbert; “their homologous sides are proportional.”
“Well, my boy, I have just constructed two similar right-angled
triangles; the first, the smallest, has for its sides the perpendicular
pole, the distance which separates the little stick from the foot of the
pole and my visual ray for hypothenuse; the second has for its sides
the perpendicular cliff, the height of which we wish to measure, the
distance which separates the little stick from the bottom of the
cliff, and my visual ray also forms its hypothenuse, which proves to be
prolongation of that of the first triangle.”
“Ah, captain, I understand!” cried Herbert. “As the distance from the
stick to the pole is to the distance from the stick to the base of the
cliff, so is the height of the pole to the height of the cliff.”
“Just so, Herbert,” replied the engineer; “and when we have measured the
two first distances, knowing the height of the pole, we shall only have
a sum in proportion to do, which will give us the height of the cliff,
and will save us the trouble of measuring it directly.”
The two horizontal distances were found out by means of the pole, whose
length above the sand was exactly ten feet.
The first distance was fifteen feet between the stick and the place
where the pole was thrust into the sand.
The second distance between the stick and the bottom of the cliff was
five hundred feet.
These measurements finished, Cyrus Harding and the lad returned to the
Chimneys.
The engineer then took a flat stone which he had brought back from one
of his previous excursions, a sort of slate, on which it was easy
to trace figures with a sharp shell. He then proved the following
proportions:--
15:500::10:x
500 x 10 = 5000
5000 / 15 = 333.3
From which it was proved that the granite cliff measured 333 feet in
height.
Cyrus Harding then took the instrument which he had made the evening
before, the space between its two legs giving the angular distance
between the star Alpha and the horizon. He measured, very exactly, the
opening of this angle on a circumference which he divided into 360 equal
parts. Now, this angle by adding to it the twenty-seven degrees which
separated Alpha from the antarctic pole, and by reducing to the level of
the sea the height of the cliff on which the observation had been made,
was found to be fifty-three degrees. These fifty-three degrees being
subtracted from ninety degrees--the distance from the pole to the
equator--there remained thirty-seven degrees. Cyrus Harding concluded,
therefore, that Lincoln Island was situated on the thirty-seventh degree
of the southern latitude, or taking into consideration through the
imperfection of the performance, an error of five degrees, that it must
be situated between the thirty-fifth and the fortieth parallel.
There was only the longitude to be obtained, and the position of the
island would be determined, The engineer hoped to attempt this the same
day, at twelve o’clock, at which moment the sun would pass the meridian.
It was decided that Sunday should be spent in a walk, or rather an
exploring expedition, to that side of the island between the north of
the lake and Shark Gulf, and if there was time they would push their
discoveries to the northern side of Cape South Mandible. They would
breakfast on the downs, and not return till evening.
At half-past eight the little band was following the edge of the
channel. On the other side, on Safety Islet, numerous birds were gravely
strutting. They were divers, easily recognized by their cry, which much
resembles the braying of a donkey. Pencroft only considered them in
an eatable point of view, and learnt with some satisfaction that their
flesh, though blackish, is not bad food.
Great amphibious creatures could also be seen crawling on the sand;
seals, doubtless, who appeared to have chosen the islet for a place of
refuge. It was impossible to think of those animals in an alimentary
point of view, for their oily flesh is detestable; however, Cyrus
Harding observed them attentively, and without making known his idea, he
announced to his companions that very soon they would pay a visit to the
islet. The beach was strewn with innumerable shells, some of which would
have rejoiced the heart of a conchologist; there were, among others, the
phasianella, the terebratual, etc. But what would be of more use, was
the discovery, by Neb, at low tide, of a large oysterbed among the
rocks, nearly five miles from the Chimneys.
“Neb will not have lost his day,” cried Pencroft, looking at the
spacious oyster-bed.
“It is really a fortunate discovery,” said the reporter, “and as it is
said that each oyster produces yearly from fifty to sixty thousand eggs,
we shall have an inexhaustible supply there.”
“Only I believe that the oyster is not very nourishing,” said Herbert.
“No,” replied Harding. “The oyster contains very little nitrogen, and
if a man lived exclusively on them, he would have to eat not less than
fifteen to sixteen dozen a day.”
“Capital!” replied Pencroft. “We might swallow dozens and dozens without
exhausting the bed. Shall we take some for breakfast?”
And without waiting for a reply to this proposal, knowing that it would
be approved of, the sailor and Neb detached a quantity of the molluscs.
They put them in a sort of net of hibiscus fiber, which Neb had
manufactured, and which already contained food; they then continued to
climb the coast between the downs and the sea.
From time to time Harding consulted his watch, so as to be prepared in
time for the solar observation, which had to be made exactly at midday.
All that part of the island was very barren as far as the point
which closed Union Bay, and which had received the name of Cape South
Mandible. Nothing could be seen there but sand and shells, mingled with
debris of lava. A few sea-birds frequented this desolate coast, gulls,
great albatrosses, as well as wild duck, for which Pencroft had a great
fancy. He tried to knock some over with an arrow, but without result,
for they seldom perched, and he could not hit them on the wing.
This led the sailor to repeat to the engineer,--
“You see, captain, so long as we have not one or two fowling-pieces, we
shall never get anything!”
“Doubtless, Pencroft,” replied the reporter, “but it depends on you.
Procure us some iron for the barrels, steel for the hammers, saltpeter.
coal and sulphur for powder, mercury and nitric acid for the fulminate,
and lead for the shot, and the captain will make us first-rate guns.”
“Oh!” replied the engineer, “we might, no doubt, find all these
substances on the island, but a gun is a delicate instrument, and needs
very particular tools. However, we shall see later!”
“Why,” cried Pencroft, “were we obliged to throw overboard all the
weapons we had with us in the car, all our implements, even our
pocket-knives?”
“But if we had not thrown them away, Pencroft, the balloon would have
thrown us to the bottom of the sea!” said Herbert.
“What you say is true, my boy,” replied the sailor.
Then passing to another idea,--“Think,” said he, “how astounded Jonathan
Forster and his companions must have been when, next morning, they found
the place empty, and the machine flown away!”
“I am utterly indifferent about knowing what they may have thought,”
said the reporter.
“It was all my idea, that!” said Pencroft, with a satisfied air.
“A splendid idea, Pencroft!” replied Gideon Spilett, laughing, “and
which has placed us where we are.”
“I would rather be here than in the hands of the Southerners,” cried the
sailor, “especially since the captain has been kind enough to come and
join us again.”
“So would I, truly!” replied the reporter. “Besides, what do we want?
Nothing.”
“If that is not--everything!” replied Pencroft, laughing and shrugging
his shoulders. “But, some day or other, we shall find means of going
away!”
“Sooner, perhaps, than you imagine, my friends,” remarked the engineer,
“if Lincoln Island is but a medium distance from an inhabited island,
or from a continent. We shall know in an hour. I have not a map of the
Pacific, but my memory has preserved a very clear recollection of
its southern part. The latitude which I obtained yesterday placed New
Zealand to the west of Lincoln Island, and the coast of Chile to the
east. But between these two countries, there is a distance of at least