Part 25 (1/2)

For several days the needle of our compa.s.s had been giving us some trouble by its strong inclination to _dip_. Three times, since starting, we had been obliged to move the sliding weight out a little on the bar. The farther north we got, the stronger was the tendency of the north pole, or end of the needle, to point downward, and the south pole to rise up correspondingly. By running the sliding weight out a little toward the south pole, its leverage was increased, and the parallel position restored. This was what Capt. Mazard was doing when we went on deck that morning.

”How do you account for this _dipping_ of the needle?” he asked Raed.

”By the present theory of magnetism, the earth itself is considered to be a magnet with two poles,” replied Raed. ”These poles attract and repel the corresponding poles of a magnetic needle, just as another large needle would. The nearer we get up to the north magnetic pole of the earth, the more the pole of our needle is pulled down toward it.

We're not such a great distance from it now. What's our lat.i.tude this morning?”

”63 27'.”

”Capt. Ross, in the expedition of 1829, made out the earth's north magnetic pole to be in 70 north lat.i.tude, farther west, in the upper part of Hudson Bay. At that place he reports that a magnetic needle, suspended so that it turned easily, pointed directly downward.”

”We've got a needle hung in a graduated scale downstairs,” remarked Kit.

We had nearly forgotten it, however.

”Bring it up,” said Raed.

Wade went after it.

It was set on the deck, and, after vibrating a few seconds, came to rest at a _dip_ of about 83.

”If we were up at the point Capt. Ross reached, it would point directly down, or at 90, I suppose,” said Kit.

”That's what he reported,” said Raed. ”There's no reason to doubt it.”

”But where is the south pole?” Wade asked.

”That has never been exactly reached,” said Raed. ”It is supposed to be in 75, south lat.i.tude, south of New Holland, in the Southern Ocean. A point has been reached where the _dip_ is 88-2/3, however.”

”Of course this magnetic pole that Ross found in 70 is not the _bona fide_ north pole of the earth,” Wade observed.

”Oh, no!” said the captain. ”The _genuine_ north pole is not so easily reached.”

”It's curious what this magnetic attraction is,” said Kit reflectively.

”It is now considered to be the same thing as electricity, is it not?”

I asked.

”Yes,” replied Kit; ”but whether they are a _fluid_ or a _force_ is not so clear. Tyndall and Faraday think they are a sort of _force_.”

”It is found that this _dip_ of the needle, or, in other words, the position of the magnetic poles, varies with the amount of heat which the earth receives from the sun,” remarked Raed. ”We know that heat can be changed into electricity, and, consequently, into magnetism.

So, at those seasons of the year when the earth receives least sun-heat, there is least electric and magnetic force.”

”That only confirms me in my belief that the luminiferous ether through which light and heat come from the sun is really the electric and magnetic element itself,” remarked Kit; ”that strange fluid which runs through the earth as water does through a sponge, making currents, the direction of which are indicated by these magnetic poles. The same silent fluid which makes this needle point down to the deck makes the telegraphic instrument click, makes the northern lights, and makes the lightning.”

”I agree with you exactly,” said Raed.

It's no use talking with these two fellows: they've made a regular hobby of this thing, and ride it every chance they get.

Prince Henry's Foreland, on the south side of the straits, was in sight at noon, distant, we presumed,--from our estimate of the width of the pa.s.sage at this place,--about eleven leagues. It is a high, bold promontory of the south main of Labrador. At this distance it rises prominently from the sea. The gla.s.s shows it to be bare, and dest.i.tute of vegetation. By two o'clock, P.M., we had pa.s.sed the scattered islets, and bore up toward the north main again to avoid the floating ice. At five we were running close under a single high island of perhaps an acre in extent, and rising full a hundred feet above the sea, when old Trull, who was in the bows, called sharply to the man at the wheel to put the helm a-starboard.