back, but then he is distinguished by not having any whalebone in the mouth; instead of which, there are rows of fine ivory teeth in each jaw, about five or six inches long. They are a more gentle fish than the other whales, and seldom fight with their tails. The spermaceti-oil, so called, lies in a great trunk about four or five feet deep, and 10 or 12 feet long, near the whole depth, breadth, and length of the head, it is disposed in several membranous cells, and covered not with a bone, but a thick gristly substance below the skin.

Their care of their young is very remarkable; they not only carry them on their tails, and suckle them, but often rise with them for the benefit of the air ; and however they may be chased or wounded by the cruelty of man, yet as long as they have sense, and perceive life in their young, they will never leave them, nor will they then strike with their tail ; and if, in their running, the young one loses its hold and drops off, the dam comes about, and passing underneath, takes it on again. Whales are very gregarious, being sometimes found 100 in a scull, and are great travellers. In the fall of the year, the right or whalebone whales go westward, and in the spring eastward. But the several kinds of whales do not mix with each other, but each sort by themselves.

Their way of breathing is by two spout-holes in the top of the head. The spermaceti has but one, and that on the left side of the head. Once in a quarter of an hour, when not disturbed, they are observed to rise and blow, spouting out water and air, and to draw in fresh air ; but when pursued they will sometimes keep under water half an hour or more; though when a cow has her calf on her tail, she rises much oftener, for the young one to breathe, without breathing herself.

The fish that prey upon the whales, and often kill the young ones, are by the whalemen called killers. These killers are from 20 to 30 feet long, and have teeth in both jaws that lock into each other. They have a fin near the middle of their back four or five feet long. They go in company by dozens, and set upon a young whale, and will bait him like so many bull-dogs; some will lay hold of his tail to keep him from threshing, while others lay hold of his head, and bite and thresh him, till the poor creature, being thus heated, lolls out his tongue, and then some of the killers catch hold of his lips, and if possible of his tongue; and after they have killed him, they chiefly feed upon the tongue and head; but when he begins to putrefy they leave him.

Ambergris is found only in the spermaceti-whales, and consists of balls or globular bodies, of various sizes, from about three to 12 inches diameter, and will weigh from a pound and a half to 22 pounds, lying loose in a large oval bag or bladder, of three or four feet long, and two or three feet deep and wide, almost in the form of an ox's bladder. Of Magnetical Powers. By M. MUSCHENBROEK. -- [1725.]

M. MUSCHENBROEK wished to try, whether loadstones operate on each other at different distances, according to a certain proportion. He thought, that if he took two magnets, and hung one of them by a thread, at different distances above the other, and if he tied the end of the thread to a balance, he might weigh the quantity of the force with which the magnets would act on each other; which succeeded accordingly.

The following table contains the experiments made at the different distances of inches and lines; and corresponding to them are columns, with the number of grains which counterpoise the force called attraction at these distances: Distance. Grains

Distance. Grains Inches. Lines. of force.

Lines. of force. 12 0...... 0

4......172 10 O...... 0

3......190 9 0...... 0}

2......215 12......703

1......250 8......106

......290 6......131 In the very point of contact or 0......340 The following table exhibits the observations he made with another very good small magnet, while the lower terrella was the same as before, and firmly fixed on a table: these experiments were made in the same manner as the former :Distance. Grains

Distance. Grains
Inches. Lines. of force.

Lines. of force.
1 0......23

2...... 79 8......30

1......140 6......381

......186 4......503

0......340 3......62 But here again occur great irregularities, from which nothing can be concluded: this only is surprising, that though the magnet used in the second experiment was smaller than that in the first, yet, in the point of mutual contact it was attracted with equal forces, namely, 340 grains, while in other distances the attraction was much less. He repeated these experiments with other magnets, and particularly with one whose force was so great, as to affect a magnetic needle at the distance of 14 Rhinland feet. But from all the experiments he could only conclude, that there is no assignable proportion between the forces and distances. He wished to observe, whether the force of the magnet was the same every day, or greater or less in summer than in winter ; but he found by several experiments, that the force is less in summer than in winter. Both poles of the magnet do not act with the same force: the north poles are stronger than the south.

While he made these experiments with magnets placed at different distances from each other, he interposed very thick pieces of lead, tin, silver, copper, and a pretty large mass of mercury, in order to see whether the magnetic effluvia would not be intercepted; and if not entirely, yet if in some measure at least: but he observed, that whatever bodies he interposed, the magnetic forces were always the same, as if no such bodies at all intervened; which he thinks, indeed, a thing surprising, and not to be understood: for we are not to suppose that these bodies are so porous as to have no solidity; if therefore they have some solid parts, as they have a great deal, shall not these hinder the approach of a foreign fuid, or its egress from the magnet, or some of it at least; but experiments show, that the magnetic forces are nowise hindered.

But he takes the strongest argument from the repelling forces of magnets, which are much weaker than the attracting forces, as appears from the experiments below; so that a fluid must necessarily come from without towards the magnet, which meeting the other magnet, impels the one fluid towards the other, and which enters the magnet; and because the magnetic attraction is much stronger than the repulsion, a greater quantity of the fluid enters into the magnet than passes out from it: whence the magnet must necessarily be soon filled with this fluid, so as to be no longer porous ; nor can it be supposed, that this fluid is emitted from all parts of the magnet, as it were; for the attraction is in every point of the magnet, but the repulsion is only in the poles.

In order to show that the magnetic repulsion is less than the attraction, the following table contains the experiments made with the last-mentioned magnets:Distance. Grains of

Distance. Grains of Inches. Lines. repulsion.

Lines. repulsion. 11 11...... 5

6...... 25 9 0...... 1

5......274 6 1...... 2

4......29 0...... 24

1......34 10......24 In the very point of contact 0......44

[ocr errors][ocr errors][ocr errors]

An Account of the Strata in Coal-Mines, fc. By John

ŠTRACHEY, Esq. F.R.S. - [1725.] MR. S. has been under ground, and viewed several coalworks in Scotland and Northumberland, and their several strata. At Widdrington they have four fathoms of clay, then a seam of coal, about six inches thick, not worth working; then a white freestone; then a hard stone, called whin ; then two fathoms of clay; then a white soft stone; and under that a vein of coal three feet nine inches thick. This is a small coal of the same nature, but not so good as the Newcastle coal which comes to London market. These veins dip to the south-east, one yard in 20.

Near Tranent, in East Lothian, in Scotland, the coal dips also to the south-east, in the same proportion ; but at Baldoe, in the parish of Campsy, three miles from Kylsith, it dips to the north-east; and at Madestone, near Falkirk, to the same point, and in the same proportion.

The strata of earths and minerals, at these places, agree very nearly: they have, as the ground rises or falls, one, two, or three fathoms of clay; then 11 fathoms of slate, or coalclives; one fathom of limestone ; under that two fathoms of slate, earth, and stone; and then coal. And all these agree in this, that the pits generally need no timber, and have a good roof, which is supported by pillars of coal, which they leave in the working.

At Baldoe, the coal is commonly 45 inches thick; and all along, for some miles eastward thence, on the sides of the hills, are crops of coal and limestone; and the tenants often spit up as much as will serve them for a winter's burning, just under the surface ; for there wants a market, and it is scarcely worth working for sale. And to the north-west and north, in the drift of the coal in higher ground, and consequently lying over it, there appear, in the sides of the hills, seams of spar and lead, the drift of which is north-east, and lies almost perpendicular ; but what obliquity there is pitches to the southeast.

At Auchenclaugh, six miles east from Kylsith, there is a coal 18 feet thick: this dips one foot in three, and is not pursued, by reason of water; and, for want of a market, will not рау.

the cost of draining. At Madestone, the coal is four feet and a half thick, and above three fathoms and a half deep: they land it on girls' backs. Near Tranent three different veins are wrought; the undermost is about 18 fathoms from the surface, called the

Splenty coal, four feet and a half thick ; it is a hard, but not
large coal; it makes a clear and strong fire ; lies ten fathoms
under the main coal, which is nine or ten feet thick, and
comes out very large. Its roof is of freestone, under which
Mr. S. walked backward and forward two hours; but had no
opportunity to make any other observations on the upper vein,
than that it is about four feet thick, and neither so hard nor
large as the other.

[subsumed][merged small][graphic][subsumed][subsumed][subsumed][subsumed][subsumed][ocr errors][subsumed][subsumed][subsumed][ocr errors][subsumed][subsumed][ocr errors][subsumed][ocr errors][subsumed]

The engraving represents the strata in a globular projection, supposing the mass of the terraqueous globe to consist of the foregoing, or perhaps of 10,000 other different minerals, all originally, while in a soft and fluid state, tending towards the centre. It must mechanically, and almost necessarily follow, by the continual revolution of the crude mass from west to east, like the winding up of a jack, or rolling up the leaves of a paper-book, that every one of these strata, though they all reach the centre, must, in some place or other, appear to the day ; in which case there needs no specific gravitation to cause the lightest to be uppermost, &c. for every one in its turn, in some place of the globe or other, will be uppermost; and were it practicable to sink to the centre of the earth, all the strata, that are, would be found in every. part.

« ForrigeFortsett »