Edmond Halley

“ Wherefore laying aside all hopes of being able to explain these Things by the ordinary Vapours or Exhalations of the Earth or Waters, we are forced to have recourse to other sorts of Effuvia of a much more subtile Nature, and which perhaps may seem more adapted to bring about those wonderful and surprizingly quick Motions we have seen. ”

“ Hence we may reasonably conclude that the Air, or Earth, or both, are sometimes, though but seldom and with great Intervals, disposed to produce this Phænomenon: for though it be probable that many times, when it happens, it may not be observed, as falling out in the Day-time, or in cloudy Weather, or bright Moon-shine: yet that it should be so very often seen at some times and so seldom at others, is what cannot well be that way accounted for. ”

“ But these are the principal Phænomena; of whose Causes I should have more willingly and with more certainty given my Thoughts, if I had had the good luck to have seen the whole from Beginning to end; and to have added my own Remarks to the Relations of others; and especially if we could by any means have come at the Distances thereof. ”

“ That supposing the Earth to be concave, with a lesser Globe included, in order to make that inner Globe capable of being inhabited, there might not improbably be contained some luminous Medium between the Balls, so as to make a perpetual Day below. ”

“ I choose to call them Laminæ, because, without doubt, though they were but thin, they spread Horizontally over a large Tract of the Earth Surface. And whilst this luminous Matter dropt down from the upper Plate to the under, the many little white Columns were formed between them by its Descent, only visible for the Moment of their Fall. These by the Swiftness with which they vanished and their great Number, shewing themselves and disappearing without any order, exhibited a very odd Appearence; those on the Right seeming sometimes to drive and push those on the left, and vice versa. ”

“ It was at the request of Caroline that Newton drew up an abstract of a treatise on Ancient Chronology, first published in France, and subsequently in England. Her regard for Halley dates from an earlier period than Newton’s death or Caroline’s accession. She had, in 1721, pressed Halley to become the tutor of her favourite son, the Duke of Cumberland; but the great perfector of the theory of the moon’s motion was then too busy with his syzygies to be troubled with teaching the humanities to little princes. ”

“ On the contrary, it seems hardly consistent with the same proportion, that Venus, an inferior planet, and without any satellite, should be larger than our earth, a superior planet, and accompanied with so remarkable a satellite. Therefore, at a mean, supposing the earth's semi-diameter, seen from the sun, or which is the same thing, the sun's horizontal parallax, to be 12 seconds and a half, the moon will be less than Mercury, and the earth larger than Venus, and the sun's distance from the earth come out nearly 16500 semi-diameters of the earth. ”

“ And as Earthquakes happen with great Uncertainty, and have been sometimes frequent in Places, where for many Years before and after they have not been felt; so These, which we might be allowed to suppose produced by the Eruption of the pent Vapour through the Pores of the Earth, when it is not in sufficient Quantity, nor sudden enough to shake its Surface, or to openit self a Passage by rending it. ”

“ Another consideration has made these authors enlarge this distance a little more: for since the moon's diameter is rather more than a quarter of the earth's diameter, if the sun's parallax be supposed 15 seconds, the body of the moon would be larger than that of Mercury, viz. a secondary planet larger than a primary one, which seems repugnant to the regular proportion and symmetry of the mundane system. ”

“ And whilst we regarded the Heavens with attention, we perceived a very thin Vapour to pass before us, which arose from the precise East part of the Horizon, ascending obliquely, so as to leave the Zenith about 15 or 20 Degrees to the Northward. But the swiftness wherewith it proceeded was scarce to be believed, seeming not inferiour to that of Lightning; and exhibiting, as it past on, a sort of momentaneous Nubecula, which discovered it self by a very diluted and faint Whiteness; and was no sooner: formed, but before the Eye could well take ‘it, it was gone, aid left no Signs behind it. ”

“ Yet was it no Cloud, but only the serene Sky more than ordinary pure and limpid, so that the bright Stars shone clearly in it, and particularly Cauda Cygni then very low in the North; the great Blackness manifestly proceeding from the Neighbourhood of the Light which was collected above it. For the Light had now put on a Form quite different from all that we have hitherto described, and had fashioned it self into the Shape of two Laminæ or Streaks, lying in a Position parallel to the Horizon, whose Edges were but ill terminated. ”

“ For, in the neighbouring places Venus's parallax will protract the duration of the transit, and make it at least 6 minutes longer; because while the sun seems to tend under the pole from west to east, these places on the earth's surface will seem to be carried with a contrary motion towards the west, that is, with a motion conspiring with the proper motion of Venus; consequently Venus will seem to move slower within the sun's disk, and continue longer on it. ”

“ Hence also it is manifest how that wonderful Corona that was seen to the Southwards of the Vertex, in the Beginning of the Night, and so very remarkable for it’s tremulous and vibrating Light, was produced; to wit, by the Concourse of many of those Beams arifing very high out of the circumjacent Regions, and meeting near the Zenith: the Effluvia whereof they consisted mixing and interfering one with another, and thereby occasioning a much stronger but uncertain wavering Light. ”

“ Next the Motion of these Beams, furnishes us with a new and, as it seems to me, most evident Argument to prove the diurnal Rotation of the earth: (though that be a matter which, at present, is generally taken by the Learned to be past dispute) For those Beams which rise up to a Point, and did not presently disappear, bat continued for some time, had most of them a sensible Motion, from East to West, contrary to that of the Heavens; the biggest and tallest of them, as being nearest, swiftest; and the more remote and shorter, slower. ”

“ And indeed I would have several observations made of the same phenomenon in different parts, both for further confirmation, and lest a single observer should happen to be disappointed by the intervention of clouds from seeing what I know not if those either of the present or following age shall ever see again; and upon which, the certain and adequate solution of the noblest, and otherwise most difficult problem depends. Therefore again and again, I recommend it to the curious strenuously to apply themselves to this observation. ”

“ And if fuch a Medium should be thus inclosed within us; what should hinder but we may be allowed to suppose that some parts of this lucid Substance may, on very rare and extraordinary Occasions, transude through and penetrate the Cortex of our Earth, and being got loose may afford the Matter whereof this our Meteor consists. This seems favoured by one considerable Circumstance, viz. that the Earth, because of its diurnal Rotation, being necessarily of the Figure of a Flat Spheroid, the thickness of the Cortex, in the Polar Parts of the Globe, is considerably less than towards the Equator ”

“ Helena, about 40 years since, on the stars round the south pole, I happened to observe, with the utmost care, Mercury passing over the sun's disk: and contrary to expectation, I very accurately obtained, with a good 24-foot telescope, the very moment in which Mercury, entering the sun's limb, seemed to touch it internally, as also that of his going off; forming an angle of internal contact. Hence I discovered the precise quantity of time the whole body of Mercury had then appeared within the sun's disk, and that without an error of one single second of time ”

“ The account of the funeral of Thomas Halley is entitled to be presented entire: “On the 24th of this month, August, Mr. Thomas Halley, clarentieux, king-at-arms, was buried, in St. Giles’s parish, without Cripplegate, with coat, armor, and pennon of arms, and scutcheons of his arms, and two white branches, twelve staff torches, and four great tapers, and a crown. And, after dirge, the heralds repaired unto Greenhill, the waxchandler, a man of note (being waxchandler to Cardinal Pole) living hard by ”

“ Halley knew that he could not himself live to witness the fulfilment of his prediction, but he says: "If it should return, according to our predictions, about the year 1758, impartial posterity will not refuse to acknowledge that this was first discovered by an Englishman." ”

“ By which means, the one overtaking the other, they would times seem to meet and jostie ; and at other times to separate, and fly one another. But this Motion was only Optical, and occasioned by the Eye of the Spectator being carried away with the Earth in to the East; whilst the exceeding rare Vapour of which those Beams did consist, being, as I take it, railed far above the Atmosphere, was either wholly left behind, or else followed with but part of its Velocity, and therefore could not but seem to recede and move the contrary Way. ”

“ But for about forty five Degrees on either side, from B to G or I, and from A to H or K, they will form themselves into Curves, more and more crooked as they are remoter from the Poles; aad withall more and more oblique to the Surface of the Stone: as our Figure truly represents, and as may readily be shewn by the Terrella and Apparatus for that Purpose in the Repository of the Royal Society Hence it may appear how this exceeding subtile Matter revolves ”

“ Halley was as good as his word. He came the next evening with a parcel under his arm. All day Ena had been looking forward with pleasure to seeing him. She had told Jack of the chance meeting, which news he had received in a surly manner.
“We can’t afford to entertain, you know, Ena, and I don’t like people seeing our penury.”
“I am sorry,” she said. “I thought it would be a man friend for you, and Mr. Halley does not seem the kind of man who wants entertaining as you call it.” ”

“ There is a test which an astronomer can often apply in the proof of his theory, and it is a very severe test. He will not only show himself to be wrong if it fails, but he will also make himself somewhat ridiculous. Halley ventured to submit his reputation to this ordeal. He prophesied that the comet would appear again in another seventy-five or seventy-six years. He knew that he would, of course, be dead long before 1758 should arrive; but when he ventured to make the prediction, he said that he hoped posterity would not refuse to admit that this discovery had been made by an Englishman. ”

“ Although in his sixty-fourth year, he then undertook to observe the moon through an entire revolution of her nodes (eighteen years) , and actually carried out his purpose. To appreciate the full significance of so painstaking an achievement it should be borne in mind that astronomical observations must be made in a temperature equal to that of the open air. Observatories cannot be heated because the heat would impair the accuracy of the instruments.
Great astronomers, like poets, are born, not made. Edmund Halley was one of these. ”

“ Among the contemporaries of Halley, we find many astronomers whose names have survived in history. We need only mention Flamsteed, the first astronomer royal, Cassini, Hevelius, Koemer and Huyghens. In his sixty-fourth year, Halley succeeded Flamsteed as astronomer royal and, at once, boldly set about the task of observing the moon through a complete revolution of the nodes, viz., a period of
Halley's Comet in 1066 on the Bayeux Tapestry. ”

“ It was Halley who encouraged Newton to put his momentous discovery and elucidation of the forces of gravity into permanent form in his “Principia,” the first volume of which, “De Motu,” was presented to the Royal Society at Halley’s suggestion.
In the proceedings of the Royal Society for December, 1684, there is an entry that “Mr. Halley had lately seen Mr. Newton at Cambridge, who had told him of a curious treatise ‘De Motu,’ which at Mr. Halley’s desire he promised to send to the Society to be entered upon their register. Mr. Halley was desired to put Mr. ”

“ Halley smiled. “I am sure you can accommodate me, even though I am not Lord Reckavile.”
“Why yes, sir, if you don’t mind roughing it a bit; we are plain folk.”
So the bargain was struck, but Halley noticed that every time the landlord came in he fixed his eyes on him in the same bewildered fashion.
When he had set the table for a simple lunch in the old timbered room Halley asked casually:
“Who is this Lord Reckavile for whom you took me? I should like to see him.”
“You must be a stranger in these parts; why, ’is Lordship ’as a place near ’ere, Reckavile Castle.” ”

“ When the door had closed, Sefton went up to Halley, and held out his hand. “If you don’t mind shaking hands with a man under suspicion,” he said “I want to apologise for my seeming rudeness.”
Halley understood and shook hands with a hearty grip.
“You need not say anything. I believe I can guess something at any rate; you may rely on me.”
Tears came into Ena’s eyes in spite of herself, if this man could trust her brother, what right had she to have doubts?
“Jack, I will believe you, but do clear up the whole thing, dear.” ”

“ Halley’s Tomb.
Bradley, the English Hipparchus, the model of observers, as he is styled by Laplace, became the third astronomer royal upon the death of Halley. He had previously effected one of his two great discoveries, the aberration of the stars, an optical illusion, arising from the combined movement of the earth in space, and the progressive transmission of light; a discovery of the highest importance, requiring the greatest precision of observation to detect. ”