Philosophical Transactions. For the months of September and October, 1715 - Part I.

By Nicole Renee

ⅼ. Some accounts of the late great solar eclipse on April 22. 1715. mane. Communicated to the Royal-Society from abroad.

Since the publication of the large account we gave in Phil. Trans. No 343 of what was observed in England, and particularly at London, of this eclipse, we have received from foreign parts the following observations; which seem not unworthy the acceptance of the curious. And first Mr. John Edens, who has obliged us with the following soft particular relation of the pike of Teneriss1 and of the ascent thereto, being on his voyage to that island, observed the eclipse at sea, in latitude, by observation 34°. 20' and longitude Oh, 54'. West from London, as he concluded by their distance and position from the island Forte Ventura, which they soon after fell with. He writes that it began at VIh.49'. and ended at VIIIh.47'. this latter very exactly, tho' not quite so nice as to the beginning.
Had this observer signified what difference of meridians there was found between the place of observation and the west end of Forte Ventura, we might, without sensible error, have concluded the true longitude, not only of that island, but also of the Pike of Teneriff, where our geographers and the Dutch have fixed their first meridian. But this gentleman being both able and desirous to render the publick this fort of service, we hope from him such further observations as may put the matter past dispute. He adds that the greatest darkness was about ¾ of the sun's diameter, or nine digits on the northside.
From Germany we have received the following Accounts.

At Nurenburg.
The beginning and greatest obscurity could not beseen for clouds, but the end happen'd at Ⅺh. IO'. ⅗.
At Hamburg.
The beginning was observed at Ⅷh 57'. The greatest obscurity at Ⅹh. 5'. 30", when Ⅺ digg. were darkened. The end could not be seen for clouds.

At Kiel in Holstein.
The beginning Ⅸh 4'. The greatest obscurity Ⅹh. 19'. 20", and the quantity then eclipsed Ⅺ. digg. 20' The end was at Ⅺh. 29'.

At Berlin.
The beginning could not be seen for clouds, but the greatest obscurity was at 22 min. past ten, when Ⅺ digg. were eclipsed. The just end was at Ⅺh. 34'.
At Frankfort on the Meine.
The eclipse began at Ⅷh 50'. The greatest darkness at Ⅹh. Ⅱ', but perhaps should be Ⅹh. 01 min. the digits being Ⅹ. and 34 min. The end was observed at 10 min. past eleven.

By whom these observations were made, and with what instruments, we are not yet informed, but hope they may be exact enough to confirm the longitudes of those several places, which are at present reasonably well known.
Since these there is lately come to hand a Dutch print entituled Nouvelles Literaries, publish'd at the Hague, wherein, pag. 404, 405, there is an account of the observation of this eclipse at Upsal2 in Sweden, made by M. Fo. Waller, Professor of mathematicks in that university, who was very careful to observe it exactly; the times being verified by three clocks perfectly agreeing with one another and with the sun: but more especially by a quadrant of 5 foot radius for taking the sun's altitude. By this instrument he has determined the height of the pole at Upsal 59°. 51' 54". And by the same, a little before the beginning of the eclipse he found the height of sun 39°. 36'. 42". his clocks then shewing the hour Ⅸh. 47'.50", which proves that they were very near the true time. At Ⅹh. 58'. 15". the altitude of the sun being 44°. 17'. 29", was the beginning of the total darkness, and at Ⅺh. 2'. 24". was the end thereof, alto sole 44°. 29'. 13". So that here the duration of the total eclipse was 4'. 9", and the middle thereof but one third of a minute after eleven. And lastly the end is said to have happen'd about 4 minutes before noon, the sun being 45°, 42'. 6". high: but in this is a manifest mistake, for it makes the time of emersion, or from the middle to the end, but 55'. 20"; whereas being so near the meridian, 'tis certain that this emersion was the greater part of the duration of the whole eclipse, and consequently more than an hour. Perhaps the times might be deduced from the altitudes only, and then the mistake might be in supporting the end so much before noon as it was really after it. However, to-prevent all doubts, we have compared this observation with what we observed of this eclipse at London, and find that in the latitude of 59°. 50', the place where the middle of total darkness was at Ⅺh. 0'. 20", was near I9 degrees more easterly than London (that is exactly in the meridian of Dantzick) and that the eclipse began there at Ⅸh. 52' x2, and ended at Ⅻh. I0'. Wherefore the duration could not be 2h. 7'. 50", as the editor of the said Nouvelles has publish'd; not considering that the beginning could not be seen for clouds, as in the very next words he assures us.
As to the darkness, it was such that they could scare distinguish one another: and besides Jupiter, Mercury and Venus; of the fixt stars Cassiopeia, Capella, Oculus Tauri and Orion, (Siris not being yet risen) were visible.

A pdf version of the entire text of the Philosophical Transactions of the Royal Society of London can be found here (this article begins on page 314).

  1. The Pike of Tenerife (modern spelling) is located on whats now known as Canary Island []
  2. Now known as Uppsala, Sweden []

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