ART. XXXVII. Latitudes and Longitudes of some remarkable Places, not contained in the preceding Tables.

St. Nicholas's or Drake's Island, in Plymouth Sound.

The bearing of Kit Hill, from the meridian of Butterton, is 67° 12′ 12′′, and the angle between it and the flagstaff on Drake's Island, 41° 40′ 8′′; therefore, the bearing of the latter from the meridian is 71° 7′ 40′′; consequently, its distance from the meridian is 60531 feet, and from the perpendicular 20692 feet, which respectively subtend 9′ 53′′6, and 3′ 24′′,5. These, with the latitude and longitude of Butterton, 50° 24′ 46′′,3 and 3° 52′ 47′′,5, give 50° 21′ 21",1 for the latitude, and 4° 8' 17′′,9 for the longitude, of the flagstaff on Drake's Island.

The latitude and longitude of this spot was determined by Mr. BAYLEY, in the year 1792. The observations for the former were as follows:

may

50 21 55 O'S LL. The mean of these is 50° 21′ 28′′,5. The place chosen by Mr. BAYLEY, as I have been lately informed, was a few feet northward of the staff; therefore, 7",4 be taken for the true difference between our determinations. The longitude of Mr. BAYLEY'S station, found by the moon's transit, was 4° 18" 52"; but the longitude deduced from the recent operations, is 4° 8'17",9; there is, therefore, a difference of 10' 34",1 between the two determinations.

St. Andrew's or the Old Church, at Plymouth.

The angle at Butterton, between the Old Church tower and Kit Hill, is 37° 45′ 5′′,2; its bearing, therefore, south-west from the meridian, is 75° 1′ 56′′; consequently, its distance from the meridian is 57505 feet, and from the perpendicular 15374 feet. These respectively subtend 9' 24", and 2′ 32′′,1: hence, its latitude becomes 50° 22′ 13′′,6, and longitude 47′ 31′′,6=16m 30',1 in time, west of Greenwich.

As it is of very great importance that the truths of the conclusions given in this Work should receive support, wherever I can find it, I think it right to mention the result of his Excellency the Count de BRUHL's endeavours to ascertain the longitude of Plymouth, by means of chronometers. The following is a copy of his communication, made in the year 1795.

Journey from Plymouth to London.
Green Timekeeper.

June 8th, Mr. MUDGE's clock* at Plymouth, fast for mean time oTM 32',15 1783. Timekeeper faster than Mr. MUDGE's clock

Timekeeper slower than London clock

14th.

London clock slow for mean time

O 25,6

14 29,4

- კ6,5

Mr. MUDGE'S clock at Plymouth, fast for mean time oTM 32',15

June 8th, Timekeeper faster than Mr. MUDGE'S clock

O 37,4

14 17,2

- ვ6,5

16 3,25

16 3,55

The longitude of St. Paul's, west of Greenwich, is 23',1 in

It is, perhaps, right to observe, that Mr. T. MUDGE's transit, at Plymouth, was made by the late Mr. BIRD, and properly set up between stone pillars. The clock, the entire work of his own hands, was a most excellent one.

time; and Mr. DUTTON's house in Fleet-street is about 2$ west of St. Paul's; wherefore, its longitude west of Greenwich is 25': consequently, 16m 3',55 + 25′ = 16m 28°,55, is the difference of longitude between Greenwich and Plymouth, as shewn by the timekeepers.

Now the meridian of Mr. MUDGE's transit-room, at Plymouth, passed only 35 feet to the eastward of the centre of St. Andrew's Tower, his northern meridian mark being on the church itself; therefore, the longitude of the church and transit-room may be considered the same. From the survey, we find it to be 16m 30,1; and, from Count BRUHL's determination, making a just allowance for the difference of longitude between the late Mr. DUTTON's house and Greenwich, 16m 28,5.

It is left for the public, and this learned Society in particular, to determine how far the near agreement of these several methods, tends to corroborate the assertion I have advanced, of the dependence which may be placed on the deductions drawn from the observations made at Beachy Head and Dunnose. If there had been only one watch employed on the occasion, the result would not have been so satisfactory as the circumstance of two being used seems to make it. As the occasion calls for the remark, before I dismiss this article, I must observe, that the highest advantages would accrue to geography, were the ideas of the Astronomer Royal carried into execution, (and which I shall endeavour to do at some future period,) respecting the discovery of the difference of longitude between Greenwich and some very remote point on the western side of the island, (St. David's Head for instance,) by means of timekeepers,

• According to HORWOOD's Map of London, the distance from the centre of St. Paul's to Bolt Court, at the corner of which Mr. DUTTON's house is situated, is 31 chains.

carried backwards and forwards in the mail coaches. If this excellent scheme were executed, and the watches employed equal to the best now made, it is probable that the true difference of longitude would shortly be determined. The geodetical situation of St. David's Head will, ere long, be ascertained from a prosecution of the survey: a knowledge, therefore, of its true longitude would be attended with eminent advantages.

Lizard Light-Houses.

The light-houses on this head-land were observed from Pertinney and Karnbonellis. At the latter, Pertinney bears 74° 22′ 41′′ south-west, from the parallel to the meridian of St. Agnes; and, as the angle between the western light-house and Pertinney is 78° 40' 5", it follows, that the bearing of the lighthouse from the said parallel is 4° 17′ 24′′ south-east. Computing with this angle and the distance from Karnbonellis to the lighthouse, we get 3344 feet, and 126499 feet, for the distances of that object from the meridian and perpendicular of St. Agnes: therefore, admitting the length of the degree in the meridian, in the middle point between St. Agnes and the light-house, to be 60850 fathoms, and 61182 for the length of a degree of a great circle perpendicular to it, we get 20' 47",4, and 32′′,8, for the small arcs which those spaces respectively subtend. These data, with the latitude and longitude of St. Agnes, 50° 18′ 27′′, and 5o° 11′ 55′′,7, give the latitude of the light-house = 49° 57' 44", and longitude west of Greenwich 5° 11′ 4′′,8, in time, 20m 443.

This light-house was also observed from the station on Karnminnis. The triangle resulting from that observation, together with the angle at Karnbonellis, is