in the Nine Free Cities … well, it was not so much a

Doubt and Doubtsoftware2023-12-07 12:47:33 92 6695

Halley's book, the Synopsis Astronomiae Cometicae, is one of the most valuable additions to astronomical literature since the time of Kepler. He was first to attempt the calculation of the orbit of a comet, having revived the ancient opinion that comets belong to the solar system, moving in eccentric orbits round the sun, and his calculation of the orbit of the comet of 1682 led him to predict correctly the return of that comet in 1758. Halley's Study of Meteors.

in the Nine Free Cities … well, it was not so much a

Like other astronomers of his time be was greatly puzzled over the well-known phenomena of shooting- stars, or meteors, making many observations himself, and examining carefully the observations of other astronomers. In 1714 he gave his views as to the origin and composition of these mysterious visitors in the earth's atmosphere. As this subject will be again referred to in a later chapter, Halley's views, representing the most advanced views of his age, are of interest.

in the Nine Free Cities … well, it was not so much a

"The theory of the air seemeth at present," he says, "to be perfectly well understood, and the differing densities thereof at all altitudes; for supposing the same air to occupy spaces reciprocally proportional to the quantity of the superior or incumbent air, I have elsewhere proved that at forty miles high the air is rarer than at the surface of the earth at three thousand times; and that the utmost height of the atmosphere, which reflects light in the Crepusculum, is not fully forty-five miles, notwithstanding which 'tis still manifest that some sort of vapors, and those in no small quantity, arise nearly to that height. An instance of this may be given in the great light the society had an account of (vide Transact. Sep., 1676) from Dr. Wallis, which was seen in very distant counties almost over all the south part of England. Of which though the doctor could not get so particular a relation as was requisite to determine the height thereof, yet from the distant places it was seen in, it could not but be very many miles high.

in the Nine Free Cities … well, it was not so much a

"So likewise that meteor which was seen in 1708, on the 31st of July, between nine and ten o'clock at night, was evidently between forty and fifty miles perpendicularly high, and as near as I can gather, over Shereness and the buoy on the Nore. For it was seen at London moving horizontally from east by north to east by south at least fifty degrees high, and at Redgrove, in Suffolk, on the Yarmouth road, about twenty miles from the east coast of England, and at least forty miles to the eastward of London, it appeared a little to the westward of the south, suppose south by west, and was seen about thirty degrees high, sliding obliquely downward. I was shown in both places the situation thereof, which was as described, but could wish some person skilled in astronomical matters bad seen it, that we might pronounce concerning its height with more certainty. Yet, as it is, we may securely conclude that it was not many more miles westerly than Redgrove, which, as I said before, is about forty miles more easterly than London. Suppose it, therefore, where perpendicular, to have been thirty-five miles east from London, and by the altitude it appeared at in London-- viz., fifty degrees, its tangent will be forty-two miles, for the height of the meteor above the surface of the earth; which also is rather of the least, because the altitude of the place shown me is rather more than less than fifty degrees; and the like may be concluded from the altitude it appeared in at Redgrove, near seventy miles distant. Though at this very great distance, it appeared to move with an incredible velocity, darting, in a very few seconds of time, for about twelve degrees of a great circle from north to south, being very bright at its first appearance; and it died away at the east of its course, leaving for some time a pale whiteness in the place, with some remains of it in the track where it had gone; but no hissing sound as it passed, or bounce of an explosion were heard.

"It may deserve the honorable society's thoughts, how so great a quantity of vapor should be raised to the top of the atmosphere, and there collected, so as upon its ascension or otherwise illumination, to give a light to a circle of above one hundred miles diameter, not much inferior to the light of the moon; so as one might see to take a pin from the ground in the otherwise dark night. 'Tis hard to conceive what sort of exhalations should rise from the earth, either by the action of the sun or subterranean heat, so as to surmount the extreme cold and rareness of the air in those upper regions: but the fact is indisputable, and therefore requires a solution."

From this much of the paper it appears that there was a general belief that this burning mass was heated vapor thrown off from the earth in some mysterious manner, yet this is unsatisfactory to Halley, for after citing various other meteors that have appeared within his knowledge, he goes on to say:

"What sort of substance it must be, that could be so impelled and ignited at the same time; there being no Vulcano or other Spiraculum of subterraneous fire in the northeast parts of the world, that we ever yet heard of, from whence it might be projected.

"I have much considered this appearance, and think it one of the hardest things to account for that I have yet met with in the phenomena of meteors, and I am induced to think that it must be some collection of matter formed in the aether, as it were, by some fortuitous concourse of atoms, and that the earth met with it as it passed along in its orb, then but newly formed, and before it had conceived any great impetus of descent towards the sun. For the direction of it was exactly opposite to that of the earth, which made an angle with the meridian at that time of sixty-seven gr., that is, its course was from west southwest to east northeast, wherefore the meteor seemed to move the contrary way. And besides falling into the power of the earth's gravity, and losing its motion from the opposition of the medium, it seems that it descended towards the earth, and was extinguished in the Tyrrhene Sea, to the west southwest of Leghorn. The great blow being heard upon its first immersion into the water, and the rattling like the driving of a cart over stones being what succeeded upon its quenching; something like this is always heard upon quenching a very hot iron in water. These facts being past dispute, I would be glad to have the opinion of the learned thereon, and what objection can be reasonably made against the above hypothesis, which I humbly submit to their censure."[1]



Latest articles

Random articles

  • at our arrival, and said one to the other, “This is the
  • the Confessor it possessed three mints, sure evidence of
  • There is an essence in all these old dwellings that comes
  • It is somewhat remarkable that, during the last ten years,
  • ‘beware’ for nothing.” They were soon anxious for
  • Then I saw the thing. There wasn't a shadow of doubt about
  • the mayor proceeded to Enmore Green, near Motcombe, with
  • thought) I went out and looked at my machine, and was fortunate
  • Even as he realized the fact, the quarry vanished, and
  • motor cycle? You are most welcome to a bed in my house,
  • opening to Far from the Madding Crowd. He was of a more
  • 'Tis the only drink that will go with bread and cheese
  • slowly toward the north—he said nothing of the party
  • When the gorse is out of blossom, kissing is out of fashion
  • when he has passed through Barford St Martin and Burcome,
  • shadowy shape. So without waiting I ran out into the hall
  • was scarcely superior to an English cottager. At night
  • were dull and inattentive, and did not seem to grasp what
  • of hard common sense to him, as clear as the crisp sunshine
  • that I might induce the driver to take me with the machine
  • in water. He just managed to get in under the sluice gate
  • the greater part of Dorset and Somerset. To add to the
  • Down in my heart I knew that no man could laugh as he did
  • of the roadside. It was simply a matter of waiting for
  • the ray of light from Max's lamp impinged upon the opening
  • unexpectedly upon narrow ravines which go tumbling down
  • his way home to the shack became the next hunter. Many
  • go into details here, but many wild stories about this
  • about the premises by night. He came and went as he saw
  • to the first Lord Arundel of Wardour, who died in 1639.
  • took some of the wonderful stuff—strong, sufficient,
  • straw hat emerged from the shadows. I questioned him as
  • and other comforts. At Caylen, the most southern island,
  • rain came slewching up Gold Hill, feeling very unhappy
  • and at the same time possess a mean mind. He was as broad
  • a few hundred yards out of Melbury Abbas, and then Fortune's
  • solid wall opened before her; it was another masked door.
  • The farmer, then, I say, was not the kind of man to qualify
  • likely, as it seemed, to die. The vicar called on her and
  • he presented as an acknowledgment for the water to the
  • and the girl's mind was in such a turmoil that she had
  • as consisting of one street in his time. In that of Edward
  • Down in my heart I knew that no man could laugh as he did
  • abbot named Wintra ruled about 647. Mr Paley Baildon, F.S.A.,
  • skin, how he had passed the night. He seemed perfectly
  • You can say what you will, but it is there, and it is
  • likely, as it seemed, to die. The vicar called on her and
  • And here is a good story related to me by a West Country
  • to have a good idea of time, was employed to strike the
  • I am afraid I talked rather wildly last night, remarked
  • tags