Lot 253
Sold for £ 33,460 (US$ 44,008) inc. premium

Lot Details
Autograph letter, signed at the head in the third person (“Johannes fflamsteedius”), in Latin, to Johann Hevelius of Danzig (“To the most eminent and distinguished Mr Johannes Hevelius, Councillor of the ancient city of Danzig, the foremost astronomer of this age, John Flamsteed sends greetings” [translation]), in the preliminary paragraph, Flamsteed thanks Hevelius for his letter of 24th June which he received via Henry Oldenburg, Secretary to the Royal Society, and assures him of his great esteem (“…I have always desired the friendship of men skilled in astronomy, in order to enter into amicable discussion with them, about astronomical studies and the best method of making accurate observations and means of putting it into practice in order to compare their result with mine…”) and the honour which he attaches to his friendship, which he hopes will allow him to point out the differences in their findings without offence; in the second paragraph, Flamsteed turns to the question of Hevelius’s observation of the sun’s meridional altitudes and the distances of certain fixed stars taken by sextant and quadrant in which Hevelius thinks that “bare sights attached to instruments are sufficient”, regretting that his own large quadrant and sextant have not yet been set up, otherwise he could have shown “the excellence of telescopic sights by means of similar experiments”; this leads him to the question of calculating the meridian altitudes of the sun, measured against the variations of its declinations, setting out a table, corrected for Danzig, of the sun’s computed declination, its computed meridian altitude, its observed altitude, with the differences for each, for the years 1670 to 1676, which, he believes, shows that the meridian altitudes recorded by Hevelius do not differ by the requisite amount (“…which…I think is to be attributed not to a fault in the instruments, or a lack of care on the observer’s part, but to the difficulty of discerning the true limits of the solar disk when it is allowed to pass through the bare aperture in the sights. If you concede this, I beg you to put to the test how brightly and strongly the same image of the sun is depicted through the object-glass alone of the telescope approximately seven feet in length, and I scarcely doubt that you will prefer it by far to the bare sighting-hole…”); he then compares their observations of Mars on the same night, Hevelius’s from Danzig, Flamsteed “At Derby, with a telescope of about fourteen feet and the Towneleian micrometer” with which he could ”very confidently distinguish celestial distances not exceeding forty minutes to a tenth part of a minute”; having set out the figures, Flamsteed concludes that Hevelius is out by two minutes (“…You claim that the places decided upon by Tycho for a group of stars in the pouring water of Aquarius also err from the truth by two minutes. But the planet’s longitude observed by me using the same fixed stars differs by no more than a third of one minute from the place observed by you using the stars of Pegasus…”), and contemplates ways in which Hevelius can correct this discrepancy; which leads him to set forth his grand purpose, as Hevelius’s confrere and successor to Tycho Brahe (“…You will perhaps say that these differences between your observations and mine are tiny. They are, I confess, such as I would readily have disregarded in Tycho’s work. But, because you thought you had achieved greater precision, I have thought it necessary to show you that you have not always aimed to the accuracy through plain sights. I believe it can scarcely be doubted that it is in fact possible to measure celestial distances more accurately with telescopic instruments…as soon as our very large instruments have been set up in their proper places and plenty of observations have been made, I shall seek out some to send you at the earliest subsequent opportunity, in order to fully satisfy you on this point…Besides those of the planets frequently noted, I have recently observed twenty and more appulses of the moon to fixed stars. The places of the moon derived from these are very often in remarkably close agreement with the places calculated from my tables, though there are sometimes discrepancies of ten or twelve minutes. I have no doubt that I would have been able to remove a good part of this extraordinary error, if only I were certain that the places of the fixed stars were correct, and the significant error lay only in the calculations.


  • Therefore I long to see your completed catalogue of the fixed stars; indeed the errors made by Tycho’s assistants corrected by you, the enlarged catalogue and whatever can be performed with your particular method of observing…”), and announcing that he has decided to defer his restoration of the lunar motions until Hevelius’s catalogue appears (“…Therefore, honoured friend, hasten this eagerly-awaited work, Do not delay because our Professor of Mechanics [Robert Hooke] promises greater precision with lesser instruments, and do not be anxious about your defence against him, since he has, even now, not made an observation with his quadrant…”); finally, he discusses the recent solar eclipse, which was only partially visible from England, and prays that God spare Hevelius’s life “as the Glory and Pillar of Astronomy”, five pages, folio, guard, some minor wear at the edges and gutter, light dust-staining, barely-noticeably tear in last leaf, but overall in fine and attractive condition, Greenwich, 20 July O.S./30 July N.S. 1676

    THE ORIGINAL OF THE CELEBRATED LETTER BY FLAMSTEED TO HEVELIUS, ARGUING FOR THE SUPERIORITY OF OBSERVATION MADE BY TELESCOPE OVER THE NAKED EYE, WRITTEN TEN DAYS AFTER SETTING UP AT THE GREENWICH OBSERVATORY AS FIRST ASTRONOMER ROYAL. Flamsteed had been appointed Astronomer Royal by warrant dated 4 March 1675, and moved into the new observatory on 10 July 1676 (ten days before the date of our letter). The task before him was Herculean, and was to initiate a new epoch in observational astronomy. In the words of the Dictionary of Scientific Biography: “The mandate of the newly created mathematicus regius was unequivocal: ‘Forthwith to apply himself with the most exact care and diligence to rectifying the tables of the motions of the heavens, and the places of the fixed stars’. By no means a new idea, it was purely and simply the project conceived by Tycho Brahe a century earlier. The only thing at all remarkable about it was the extent to which it had been neglected during the intervening years. Incredible as it appeared to later ages, the invention of the telescope had as yet had virtually no impact on fundamental astronomy. Two generations after Galileo’s momentous discoveries, Tycho’s star catalogue remained the standard of excellence; and the one designed by Hevelius to replace it was likewise being constructed on the basis of naked-eye observations. With respect to the planets, the laws of Kepler were just winning general acceptance, while the observations from which they had been derived were being published (1666) because they still represented the most accurate information available. Flamsteed’s assignment, then, was essentially that of dragging positional astronomy into the seventeenth century” (Dictionary of Scientific Biography). A site in Greenwich Park was chosen for the new observatory by Sir Christopher Wren and the building was hastily run up from his design at the cost of £520, realised by the sale of spoilt gunpowder. When Flamsteed, who hitherto had been conducting his observations at the Tower of London and then at the Queen’s House in Greenwich, moved into the Royal Observatory, “He found it destitute of any instrument provided by the government; but Sir Jonas Moore gave him an iron sextant of seven feet radius, with two clocks by Tompion, and he brought from Derby a three-foot quadrant and two telescopes…His official assistant was a ‘surly, silly labourer’, available for moving the sextant; and his large outlay in procuring skilled aid and improved instruments obliged him to take private pupils…Under these multiplied disadvantages, and in spite of continued ill-health, he achieved amazing results” (Dictionary of National Biography). He began his series of observations on 19 September 1676, and by 1689 he had executed some twenty thousand; his Historia coelestis Britannicae, published in 1725, listing 2,935 stars.

    The distinguished recipient of this letter, Johannes Hevelius, the Polish astronomer, was author of the first detailed lunar map and the most extensive star catalogue before Flamsteed, published in 1690 as Firmamentum Sobiescianum sive Uranographia. His own observatory could well have acted as a model for the new Royal Observatory: “Hevelius, in Danzig, had achieved and published so much that for a new institution to claim to compete with him on his own terms might have seemed presumptuous; but the engravings of his observatory published in Machina coelestis pars prior in 1673 appear to have formed the immediate model for the dozen views of the Royal Observatory, instruments and surrounding park commissioned from the Ordnance Office…soon after the foundation” (Frances Willmoth, ‘Flamsteed, Horrocks and Tycho’ in Flamsteed’s Stars: New perspectives on the life and work of the first Astronomer Royal, edited by Frances Willmoth, 1997, pp.60-1; where Mordechai Feingold discusses the genesis of this letter in ‘John Flamsteed and the Royal Society’ and Jim Bennett discusses Flamsteed’s attitude towards Hevelius as successor to Tycho Brahe in ‘Nobility, Morality and Public Utility’). Hevelius was the first to publish this letter, accompanied by marginal summaries, in Annus climactericus (Danzig, 1685), pp.74-78; although an extract had earlier appeared in J.E. Olhoff, Excerpta ex literis…ad…Dn. Johannem Hevelium (Danzig, 1683), p.163. There is also a transcript in the Bibliotheque Nationale, Paris (Ms Lat 10348, pp.64-71), which has been adopted as the copy text for The Correspondence of John Flamsteed, first Astronomer Royal, vol.i, 1995, compiled and edited by Eric G. Forbes, Lesley Murdin and Frances Willmoth, pp.487-95, whose translation, quoted above, we gratefully acknowledge.
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