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Jean Dominique Cassini
Henry Oldenburg
Cassini states that he has pushed forward the ephemerides of the 'Medicean stars' (Jupiter's moons) A paper by Nicholas Mercator is attached which considers Cassini's geometrical and direct method for finding the anomalies of the planets. Figures and mathematical formulae are attached Oldenburg has written a note on the back of the paper about Dr Wren promising Collins the direct method for dividing the area of an ellipse and a table method for finding the length of the ellipse Mercator's paper originally published by the Journal des Scavans is printed in 'Philosophical Transactions', vol 5, no 57, p 1168 Read to the Royal Society on 16 June 1669
10 June 1669 Sender: Jean Dominique Cassini , Jean Dominique Cassini Reference number: EL/C1/50
1671
Cassini asks Oldenburg if he could employ Paul Boccone, a Sicilian botanist, who comes recommended by Gornia, physician to the Grand Duke of Tuscany Cassini's method (in English) for observing the altitude of the sun at St Petronius in Bologna is attached
02 February 1671 Sender: Jean Dominique Cassini , Jean Dominique Cassini Reference number: EL/C1/51
Cassini says that he sends a copy of his observations of the sunspots, then gives details of his observations of Saturn, and informs Oldenburg that Monsieur Picard was going to Tycho Brahe's observatory on the island of Hven in the Danish Sound to observe the lunar eclipse and the difference between the meridians and the height of the Pole Read to the Royal Society on 2 November 1671
20 August 1671 Sender: Jean Dominique Cassini , Jean Dominique Cassini Reference number: EL/C1/52
1672
Cassini sends his observations of Jupiter and of the comet which were published in the 'Journal des Scavans' He also compares the observations of the lunar eclipse at Aleppo with observations of the same eclipse made in Italy Read to the Royal Society on 24 April 1672
23 April 1672 Sender: Jean Dominique Cassini , Jean Dominique Cassini Reference number: EL/C1/53
Cassini provides his observations of a possible satellite of Saturn during October and November 1671; concerning Robert Hooke's observations of a lunar eclipse during September; Cassini gives his explanation of why Saturn looked round Read to the Royal Society on 11 January 1672
09 January 1672 Sender: Jean Dominique Cassini , Jean Dominique Cassini Reference number: EL/C1/54
Cassini thanks the Royal Society for electing him to the Fellowship and promises a paper on the ephemerides of Jupiter's satellites Read to the Royal Society on 26 June 1672
22 June 1672 Sender: Jean Dominique Cassini , Jean Dominique Cassini Reference number: EL/C1/55
1673
Covering note where Cassini sends a copy of his little book about the discovery of new satellites around Saturn Read to the Royal Society on 26 March 1673
25 March 1673 Sender: Jean Dominique Cassini , Jean Dominique Cassini Reference number: EL/C1/57
Cassini encloses a copy of his letter to John Flamsteed (see EL/C1/59)
11 August 1673 Sender: Jean Dominique Cassini , Jean Dominique Cassini Reference number: EL/C1/58
Cassini describes the telescopes that he has used to view Saturn Read to the Royal Society on 11 December 1673
22 September 1673 Sender: Jean Dominique Cassini , Jean Dominique Cassini Reference number: EL/C1/60
Discusses the diameters of the satellites of Jupiter and describes the telescope used to observe Jupiter and Saturn Encloses a copy of his reply to John Flamsteed (see EL/C1/61) Read to the Royal Society on 11 December 1673
08 November 1673 Sender: Jean Dominique Cassini , Jean Dominique Cassini Reference number: EL/C1/62
1674
Cassini gives his views about Robert Hooke's theory for the annual motion of the earth and then gives his own observations about this Partially printed in 'Philosophical Transactions', vol 9, no 105, pp 90-91
28 June 1674 Sender: Jean Dominique Cassini , Jean Dominique Cassini Reference number: EL/C1/63
1675
Concerning similarlities between the observations of the eclipse of the moon seen at Paris and London in June 1675 A list of observations is provided Printed in 'Philosophical Transactions', vol 10, no 117, p 390
07 August 1675 Sender: Jean Dominique Cassini , Jean Dominique Cassini Reference number: EL/C1/64
1676
Cassini states that he is sending an account of the future path of the sunspot (a published article in French, from an unidentified journal, entitled 'Description du Mouvement que doit faire dans le Soleil und Tache sur la fin de Novembre 1676' is attached) Cassini also says that Flamsteed's prediction for the conjunction of the moon with a fixed star was accurate and that he wishes to receive Flamsteed's ephemeris for the coming year
25 November 1676 Sender: Jean Dominique Cassini , Jean Dominique Cassini Reference number: EL/C1/65
Concerning a figure showing the path of the sunspot where Cassini states that he has added positions for its future path in December Figure no longer attached Cassini asks for the observations of the sunspot from English astronomers
02 November 1676 Sender: Jean Dominique Cassini , Jean Dominique Cassini Reference number: EL/C1/66
Concerning the mean time of the lunar eclipse and its magnitude giving the observations of John Flamsteed and Edmond Halley Printed in 'Philosophical Transactions', vol 11, no 123, p 561
11 February 1676 Sender: Jean Dominique Cassini , Jean Dominique Cassini Reference number: EL/C1/68
Concerning the occultation of a star in the 'lion's foot' by the moon in February Printed in 'Philosophical Transactions', vol 11, no 123, p 564
04 March 1676 Sender: Jean Dominique Cassini , Jean Dominique Cassini Reference number: EL/C1/69
Cassini makes calculations for the beginning and end of the eclipse of the sun, which occurred on 1 June 1676, because cloud obscured direct observations of it Figure in text
25 July 1676 Sender: Jean Dominique Cassini , Jean Dominique Cassini Reference number: EL/C1/70
Concerning observations of a spot seen recently on the sun and observations of the rings of Saturn (original figures in CLP/8i/32) Printed with figures in 'Philosophical Transactions', vol 11, no 128, p 689
26 August 1676 Sender: Jean Dominique Cassini , Jean Dominique Cassini Reference number: EL/C1/71
Concerning the observations of stars in the southern hemisphere made by Messrs Richer and Meurisse, and the meridian of St Helena island in the south Atlantic
09 August 1676 Sender: Jean Dominique Cassini , Jean Dominique Cassini Reference number: EL/C1/72
Cassini sends the position of the eclipse of the first satellite of Jupiter at the meridian of Paris in 1677 so that this eclipse can be observed at St Helena island in the south Atlantic in order to determine the difference between the two meridians
12 February 1676 Sender: Jean Dominique Cassini , Jean Dominique Cassini Reference number: EL/C1/73
Cassini sends calculations of the eclipse of the first satellite of Jupiter and some observations of the emersion of the first satellite from the shadow of Jupiter observed from Paris and Avignon
23 February 1676 Sender: Jean Dominique Cassini , Jean Dominique Cassini Reference number: EL/C1/74
Concerning the meridian altitudes of the sun observed at Caen, and the altitudes of the stars, so that the same might be observed at St Helena island in the south Atlantic Oldenburg added a note on the back of the letter about meridinal altitudes of the moon and fixed stars, and about the spots on the sun
24 October 1676 Sender: Jean Dominique Cassini , Jean Dominique Cassini Reference number: EL/C1/75
Concerning observations of the spot on the sun, and that the spots on Mars will be viewable soon as the planet is approaching earth
04 November 1676 Sender: Jean Dominique Cassini , Jean Dominique Cassini Reference number: EL/C1/76
Cassini states that the spot on the sun has returned for a third time, that he has been observing Mars to determine its parallax, and raises objections against Roemer's theory for the motion of light
16 December 1676 Sender: Jean Dominique Cassini , Jean Dominique Cassini Reference number: EL/C1/77
1677
Cassini gives thanks for the astronomical calculations computed by Oldenburg and Flamsteed which were sent to him and that his calculations for predicting the path of the sunspot were similar to those published by Flamsteed in 'Philosophical Transactions', and that he continues to use this theory for predictions
02 January 1677 Sender: Jean Dominique Cassini , Jean Dominique Cassini Reference number: EL/C1/78
Cassini gives his observations of the comet made in Paris Printed in 'Philosophical Transactions', vol 12, no 135, p 868
09 May 1677 Sender: Jean Dominique Cassini , Jean Dominique Cassini Reference number: EL/C1/79
Cassini gives his observations of the comet which were made near Madrid
16 June 1677 Sender: Jean Dominique Cassini , Jean Dominique Cassini Reference number: EL/C1/80