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Western Light-house 37 48 44; which gives 81342 feet, for the distance between the station Karnbonellis and the Light-house. This distance is said, in the Philosophical Transactions for 1797, p. 501, to be 81348 feet, which differs only 6 feet from the above determination; but it is probable the distance first given is most correct, as the two light-houses appearing nearly in the same line at Karnminnis, was the means of preventing us from clearly distinguishing the apex of either, and it was principally on this account that we preferred the observation made at Pertinney. The agreement however proves, that no inconsistency can be found to obtain with respect to the data before given, for settling the situation of this important headland.

In the Philosophical Transactions for 1797, page 502, it is mentioned, that the distance from the spot where the late Mr. BRADLEY made his observations, to the place where his meridian mark was fixed, was 800 feet. But there appears to be some inconsistency in this particular; as Mr. BRADLEY'S own words, in an extract of a letter now before me, are, it was just 480 feet. Adding to this, 24 feet, the distance between the place of the meridian mark and the line joining the centre of the lighthouses, we get the distance of the point O, or the place of the Observatory, (see Phil. Trans. 1797, p. 502,) from the line joining the light-houses W, E, = 504 feet; a space corresponding to 5" of latitude, nearly; therefore, from the trigonometrical operations, we get,


49° 57′ 44′′ for the latitude

5 11 4,8 for the longitude} of


Mr. BRADLEY'S station.

Mr. BRADLEY'S observations for finding the latitude, were

made with a quadrant of one foot radius, the workmanship of Mr. BIRD; they were as follows.

Nine meridional altitudes of the sun's limb, the extreme results of which were 49° 57′ 27',5 and

49° 57′ 44′′, gave for the latitude of the Obser-

Six meridional observations of the Pole Star be-
low the Pole, the extreme results of which were
49° 57′ 35′′ and 49° 57′ 20′′,4, gave for the la-
Thirteen observations of Arcturus, & Coronæ Bo-


realis, and a Serpentis, the extreme results of which were 49° 57′ 54",7 and 49° 57′ 2′′,7, gave for the latitude

Fifteen observations of a, B, y Draconis, the extreme results of which were 49° 57′ 22′′,2 and 49° 57′ 2′′7, gave for the latitude

The mean of which is

49° 57′ 35"

49 57 23,2

49 57 29

49 57 33

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According to the trigonometrical operations, the latitude is 49° 57′ 44′′; there is, therefore, a difference of 14" between the results; a quantity so large as justly to excite surprise, if it were not generally understood, that much dependance cannot be placed on observations made with an astronomical quadrant precisely similar to that made use of by Mr. BRADLEY. The extreme results in the above, differ so widely as to authorise the truth of the supposition on this occasion.

The longitude of the Lizard was determined by the transit of Venus, Sun's eclipse, transit of the Moon, and two emersions

of Jupiter's first satellite, as particularly set forth in the Preface to the Nautical Ephemeris of 1791. The conclusions were as follows.

Four transits of the Moon, calculated by Mr. Wales,

gave for the longitude

Two emersions of Jupiter's first satellite, calculated by ditto

Transit of Venus, calculated by Mr. WITCHELL



20" 30',6

21 14 5

(Doctor MASKELYNE 20 57,0

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20 45,1

Sun's eclipse, calculated by

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From the trigonometrical operations, we find the longitude in time to be 20 44,3; there is, therefore, a difference of 75,82 between these different determinations: this is, probably, as near as we could have expected to find it; yet it can scarcely be supposed, that of this difference, more than 25 can be laid to the account of the survey.

In the Philosophical Transactions for 1797, p. 502, it is observed, that angles were taken at the Lizard Light-house and Naval Signal-Staff, to determine the situation of the Point itself. This Point, marked P in the diagram, makes an angle of 2° 23′ 16′′ SW, with the parallel to the meridian of St. Agnes at the station on Karnbonellis, and is therefore 636,6 feet from that meridian, and 126394 feet from the perpendicular; therefore 49° 57′ 40′′,6 is the latitude

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of the Lizard Point.

the longitude} of

Scilly Islands.

To determine the distances of the objects in these islands, from the stations near the Land's End, with sufficient accuracy, proper corrections were made for reducing the horizontal angles to those formed by the chords. On the present occasion, it will be right to use the horizontal, and not the chord angles; the distances from the meridians, and from their perpendiculars, being computed on the supposition of the earth's surface being a plane, which, within the limits of our fixed meridians, may be considered as true.

The angles for finding the distances of these objects are given in the Philosophical Transactions for 1797, p. 503; from whence, and the data contained in this Work, we get the bearing of

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which, combined with the distances of the stations from the meridian of St. Agnes, give

246801 feet, for the distance of the Day-mark from the 246804 meridian of St. Agnes;


and 199410 feet, for the distance of it from the perpendicular.


The mean of the first is 246809 feet, and the mean of the last 122411 feet; but the latter becomes 122419, because a line drawn from the Day-mark, perpendicular to the meridian of St. Agnes, cuts that meridian eight feet below the parallèl. Again, we get the bearing of

the Windmill
in the Island of St. Pertinney
the Flagstaff of the Fort Mary, from


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from whence, after a similar correction with that just made, we

find the distance of

the Windmill 256304 feet from the

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the Flagstaff 260152 meridian, and {

143597 feet from the perpendicular of
140876 J
St. Agnes.

From the same page, and the data furnished in this work,

we also find the bearing of

St. Agnes Light- [Sennen

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House from St. Buryan 69 5 56 SW; which gives 265865 feet, for the distance from the meridian, and 265879J



feet, for the distance from the perpendicular of St. Agnes.

The mean of the first is 265872 feet, and the mean of the last, when corrected, 149133 feet.

With the above data, and also the latitude and longitude of St. Agnes, we get

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Day-mark in St. Martin's

49° 58' 2",9

Windmill, St. Mary's

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Day-mark 1° 2′43′′,1
Windmill I 5 3,2
Flagstaff 1 6 2,7
Light House 1 7 27,7

from the meri-
dian of Green-6 17 57 4

6 19 23 4 25 21,5

• In the Requisite Tables, published by order of the Board of Longitude, the latitude of the Scilly Lights is said to be 49° 56′o", and longitude 6° 46′ o". The latitude, according to the survey, is 49° 53' 36",8, and longitude 6° 19' 23',4. An error of 2′ 23′′ in the latitude, may not perhaps be considered extraordinary; but how, in a maritime country, like our own, where chronometers are in such constant use, so great an error as 26′ 37" (1m 46 in time) in the longitude, should have remained. undetected, excepting by one person, is surprising. J. HUDDART, Esq. visited the Scilly Isles, having with him a watch made by ARNOLD, and obtained his time at that spot in the island of St. Mary where the body of Sir CLOUDSLEY SHOVEL is said to have been thrown ashore, by means of equal altitudes of the Sun's limb; he then found, comparing his time with that shewn by the watch, that oh 25m 18 was the difference between the meridians of Greenwich and this spot in St. Mary's. Now St. Agnes Light-house is about 2' of a degree west of the place to which Mr. HUDDART alludes; therefore, 25' 18"+8" 25' 26" is the longitude of St. Agnes, through these means; which differs only 4,5 in time from that found by the survey.

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