An account of the trigonometrical operation, wherby the distance between the meridians of the observatories of Greenwich and Paris has been determined / By William Roy.

  • Roy, William, 1726-1790.
Date:
[1790]
Catalogue details

Licence: Public Domain Mark

Credit: An account of the trigonometrical operation, wherby the distance between the meridians of the observatories of Greenwich and Paris has been determined / By William Roy. Source: Wellcome Collection.

    119/200 (page 113)
    by two fetsof angles given in the Meridienne venjiie^ as adverted to m the Paper of 1787, Phil.Tranf. Vol. LXXVlI.p. 195, 19&, Art, XII. longitudes of Dunkirk and Paris, eaf ward front- Greenwich, determined by the fum of four differences of me- ridians. In fig. 9. let PA be the meridian of Greenwich ; G Goud- hurfl, PR its meridian ; T the Ration at Folkftone Turnpike.* PS its meridian ; C Calais, PC its meridian ; D Dun- kirk, and PB its meridian. Alfo, let AG, RT, SC, and BC, be arcs of great circles, making the angles PAG, PRT, PSC,. and PBC, right ones. The angle at GoudhurR, between its meridian and Tenter-, den, is 107° 26' 40T34 hence, by drawing parallels to this meridian through Tenterden and the Ration at Allington Knoll (fee the plan of the triangles) we Rial! get 946 6 fathoms for what the Ration at the Turnpike is fouthward, and 28098.8 fa- thoms for what it is eaflward from the meridian of GoudhurR*, Now, 60859,4 fathoms being nearly = i° of the meridian in the latitude of Goudhurfl, we have 946.6 fathoms =5 56^ nearly the arc GR; and the latitude of GoudhurR being 510 6; 49//.6> that of the point R is 510 f .6 ; hence the co-latitude RP = 38® 54' 6 A 4 and fines the degree of a great circle, per- pendicular to the meridian, in this latitude has been (hewn to contain 61248 fathoms nearly; therefore RT = 28098.8 fa- thoms will be if 3i//.6. This arc and RP giver the angle RP5 = o° 43' 49A86 for the difference between the meridians of GoudhurR and Folk Rone Turnpike. The angle at Folkflone Turnpike between its meridian and Dover was obferved 66° 48' and if we draw a parallel to this meridian through Dover, we (hall find* that Calais is i'i 25284*21