Philosophy 167: Class 13 - Part 4 - Further Newton-Flamsteed Correspondence Concerning the 1680/1681 Comet: Flamsteed's Calculations of the Comet's Trajectory, and Newton's Response.

Smith, George E. (George Edwin), 1938-

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Synopsis: Flamsteed sent calculations of the two comets' trajectories to Newton, trying to prove they were the same orbit.

Philosophy and science.
Celestial mechanics.
Newton, Isaac, 1642-1727.
Flamsteed, John, 1646-1719.
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ID: tufts:gc.phil167.148
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So Flamsteed gets this letter, defends himself at length. I'm not going to give you the whole defense. Again, it's in supplementary material, as I say, this goes on and on, this exchange. Defends himself and then this is part of the defense showing all of these observations from, as the earth moves and the comet, you can see the trajectory of the comet.
But if you notice, when the comet gets near the sun, he hasn't gotten any observations. He's working from observations further away and it's the symmetry of the two paths that are convincing Flamsteed that it's one comet. And he in effect, and I'm saying in effect because that's an understatement.
He ends of saying to Newton, can you help me, which of the two configurations. Does it go around the sun or before the sun, and Newton then, in early April, this is seven of March, early April drafts a long letter that he does not send. And I'm not gonna quote from it.
But it's available to you. Then in April, 23rd is it, no it's April 16th, I'm sorry, no, no, Trinity College April 16, 1681, yeah, 16, I just can't see one. Starting the letter that complements. You were pleased out of extreme kindness to give me. They were passing these wonderful you're such a great person type comments back and forth.
My better half suited with yourself for me. Nor do I think it suits with me to judge of a hypothesis after your thoughts upon it. I only propounded objections for you yourself if you had not thought of them before, to judge further of it by. Which therefore, being designed only for your use, I forebear to urge further and shall only speak of the question of two comments.
Then he gets off on Galileo's observations, which were one of the ones most screwing things up, but the part I wanna come to in this, he goes through looking at observations, but the key thing comes down here at the end. But whatever there be these difficulties, this weighs most with me.
That to make the comets of November and December but one is to make that one paradoxical. Did it go in such a bent line, other comets would do the like? And yet, no such thing was ever observed in them, but rather the contrary. The comets of 1665, 1677 in Ethers, which move towards the sun, or some of them at least.
Had they twisted about the sun and not proceeding on forward, gone away behind him, they would have been seen again coming from him. The many which have been seen advancing from the sun, or some of them at least, would have been seen in the former part of their course advancing toward him, etc, than this more common theory.
And just in effect says, to summarize you can read the whole thing for yourselves. Summarize the thing. If this were one comet, the two were one comet, surely we would have seen alike cases before. Paired comets, one moving north to south, or one moving in one direction the other in the opposite direction afterwards, with some symmetry between them.
So, he's rejected the idea. It's gone. And we know from the draft letter, he didn't send, he's actually saying this much stronger. That is, here he's softening it. He is very much convinced in the Spring of 1681 that there was not one comet that went around the sun.