Thursday 4 February 1668/69

Up, and at the office all the morning. At noon home with my people to dinner, and then after dinner comes Mr. Spong to see me, and brings me my Parallelogram, in better order than before, and two or three draughts of the port of Brest, to my great content, and I did call Mr. Gibson to take notice of it, who is very much pleased therewith; and it seems this Parallelogram is not, as Mr. Sheres would, the other day, have persuaded me, the same as a Protractor, which do so much the more make me value it, but of itself it is a most usefull instrument. Thence out with my wife and him, and carried him to an instrument-maker’s shop in Chancery Lane, that was once a ‘Prentice of Greatorex’s, but the master was not within, and there he [Gibson] shewed me a Parallelogram in brass, which I like so well that I will buy, and therefore bid it be made clean and fit for me. And so to my cozen Turner’s, and there just spoke with The., the mother not being at home; and so to the New Exchange, and thence home to my letters; and so home to supper and to bed. This morning I made a slip from the Office to White Hall, expecting Povy’s business at a Committee of Tangier, at which I would be, but it did not meet, and so I presently back.

5 Annotations

Terry Foreman  •  Link

"In this year Wren presented the world, through the Royal Society, with a paper relative to his discovery of a right line equal to a cycloid, and added continually to their stock of experimental knowledge....Hobbes of Malmesbury, who had been teacher of mathematical philosophy to Charles II. in his youth, had been engaged in a controversy relative to the quadrature of the circle, and published a work on that much debated subject, which proved him to have been but little skilled in mathematics, however profound he might have been as a metaphysician. Dr. Wallis undertook to combat the Leviathan of the day, and satisfactorily demolished his hypothesis, in the work which he published this year, and presented twelve copies to the Society, for its library, president, secretaries, Sir Robert Moray, Sir John Lowther, Dr. Wren, Messrs. Hoskins, Hooke and Collins. Experiments were continued confirmatory of Wren's laws of motion, from which was deduced, that motion cannot be decreased or increased infinitely, but that there are limits set both for the increase and decrease of all the motion in the world. Letters were received by the Society from Huygens in Paris, Slusius, from Liege, and from other eminent Philosophers on the Continent, in commendation and corroboration of Wren's demonstration of the hyperbolic cycloid, his laws of motion and other important discoveries which then occupied all the learned men in Europe."

Jesse  •  Link

re: which proved him to have been but little skilled in mathematics

Oh come now. It wasn't formally proved impossible until 1882

re: motion cannot be decreased or increased infinitely

There's always friction. I take decreasing to mean you can't go infinitesimally slow, i.e. you can only go so slow before you stop. Increasing might mean something like a terminal velocity

Bryan M  •  Link

Wren's laws of motion

These laws concerned collisions between bodies and what is now known as the conservation of momentum. Carolyn Merchent's 1967 PhD thesis has a nice summary of the theory (see link below, go to page 44) and a copy of the original document in Latin (which is all Greek to me).

Carl in Boston  •  Link

"my people"
my people will meet your people.

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