PHILOSOPHICAL TRANSACTIONS. 



337 



TOL. LVI.] 



A table of the variations of the magnetic needle, as observed on board his Majesty's ship Montagu, in the years 

 1760, 176"l, and 176'2, by Mr. David Ross; and communicated by Mr. William Mountaine, f. r. s. 



Time when. 



May 



176O 



April 12 



2() 



29 



2 



5 



6 



7 



9 



10 



11 



J2 



13 



14 



15 



17 



18 



19 



20 

 21 

 22 

 23 

 25 

 26 

 28 



29 & 3 1 



June 



1 



2 

 3 

 4 

 6" 



8 



15 

 \6 

 17 

 18 

 20 

 22 

 11 

 12 

 15 

 16 

 18 

 5 

 6 

 10 

 14 

 li 



22 



23 



1761 24 

 Mar. 23 

 April 4 

 15 

 May 4 

 July 27 



VOL 



July 

 Sept. 



Oct 



Variation. 



In Carlisle, Barbadoes 



Barbadoes, s. e. 10^ leagues dist. 



15° lii' X. 59° 0' w. 



16 16 N. 59 18 w. 

 Antigua w. n. w. dist. 6 leagues 

 Redondo e J n . 4 leagues 

 Montserrat 8. by e. I 



Redondo s. by w. J 



In thepas.bet. Martin, and Domin 

 Off the 8. w. end of Martinique 

 Off the 8. end of Dominico 

 S. of Rupert's Bay, Domin.dis. 3lg. 

 In Prince Rupert's Bay — 3" 27 7 



Dominico 3 12 J 



Deseada s. w. by w. dist. 3 leag. 



16"0'n. 5.(;''7'w. 

 In Grand Courland's Bay 1 



At the s. w. end of Tobago, the > 

 medium is ) 



N end of Tobago e. n . e. dist. 5 Ig. 

 ;D° E. by s. dis 4 leagues 

 jlsl.Bequia s.w.by N. J w.dis. 7 Ig. 

 iQff the N. w. end of St. Lucia 

 lOff Saint Pierre's Martinico 

 lAt the wind of the Channel be- 

 tween Martinique and Dominico 

 jAt the E. end of the s.ime 

 Saint Luc'a w. J x. dist. ) S Igs. 

 In Prince Rupert's Bay, Dominico 

 In St. John's Road, Antigua 

 Off the east end of Antigua 

 In Carlisle Bay, Barbadoes 

 At the Dog and Prickly Pear 



XII. 



19° 



'8 



<9 



17 



1 + 



14 



13 



10 



10 



10 



7 

 5 

 5 

 4 

 1 

 I 



O 

 

 1 

 1 

 2 

 3 

 3 



Time when. 



3 

 35 



4 .32 E. 



July 



Aug. 



Sept. 



1761 

 28 



29 



30 



31 



1 



2 

 3 

 4 

 5 

 6" 

 7 

 8 

 9 

 10 



11 



12 



13 



15 



16" 



17 



18 



19 



20 



21 



22 



23 



24 



26" 



27 



28 



29 



30 



31 



1 



2 



4 



5 



6 



7 



10 



20 



21 



Dec. 8 



19,25, & 26" 

 17 62 Jan. 23 



Jan. & Feb. 



Feb. 1 1 

 D°l2,23,&i 

 March 2 j 

 5 



From 3 to 12 leag 

 E. off Gibral. Hill 



Latitude in 



19° 35' l«. 



Long.fr. Lon. Variation. 



20 

 22 

 23 

 25 

 26" 

 27 

 27 

 28 

 28 

 28 



'-'9 

 30 

 31 

 32 

 33 

 35 

 36 

 37 

 37 

 38 

 38 

 38 

 38 

 39 

 40 

 41 

 41 

 42 

 42 

 43 

 43 

 43 

 44 

 45 

 48 

 48 



+9 

 50 



46" N. 

 20 N. 

 42 N. 

 5 N. 

 20 \. 

 26" N. 

 56" N. 



5 N- 

 11 N. 



40 N. 

 23 N. 



1 N. 

 1 N. 



41 N. 



58 N. 



3 N. 

 31 N. 



33 N. 



59 N. 



8 X. 

 36 .V. 



23 N. 



57 N. 



22 s. 



13 N. 



8 N. 



31 N. 



N. 



38 N. 



15 N. 

 K. 



28 K. 

 45 N. 

 36' N. 



14 N. 



57 X. 



11 N. 



35 N. 



62° 



6> 



62 



62 



62 



62 



6"2 



62 



62 



62 



62 



63 



62 



62 



60 



59 



57 



54 



52 



51 



50 



48 



47 



46 



45 



44 



42 



41 



39 



38 



S6 



35 



34 



31 



29 



25 



23 



20 



18 



50' w. 

 43 w. 

 30 w. 



36 w. 



37 w. 

 57 w. 

 37 w. 

 43 w. 

 50 w. 

 35 w. 

 59 w. 



I w. 

 59 w. 

 21 w. 

 37 w, 

 14 w 



54 w 



57 w 



55 w. 

 4 w 



13 w. 



41 w, 



48 w 

 30 w 



52 w 

 29 w. 

 2ii w. 



42 w. 



58 w. 

 11 w 

 •21 w. 



53 w 

 40 w. 

 58 w. 



49 w. 

 17 w. 

 13 w. 

 28 w. 

 17 w. 



Iff Cape Clear in Ireland 

 Scilly s. s. E. dist. 5 leags. 

 The Start E. I N. dis. l6ml. 



30" ','5' N. 7°45'w. 



In Gibraltar Bay 



35''46'.\. 7° 2' w. 



Bel. Cape St. Vincent & 1 



the Straits Mouth / 



In Cascais Road 



In Lisbon River 



37°o6"'n. 9°5.5'w. 



Bet. C. St. Mary's & C. / 

 Sparte), the medium is ( 



}„„ .k„ f Euro. Shore 

 °" ''•n Bar. Shore 



4° 



4 



2 



2 



1 



I 



























1 



1 



2 

 4 

 5 



7 



8 



9 

 10 

 10 

 10 



11 



12 

 12 

 12 

 13 

 13 

 13 

 14 

 14 

 4 

 17 

 18 

 18 

 19 

 19 

 19 

 19 

 19 

 20 

 U) 

 17 

 18 



17 



17 



17 



17 



:7 



17 

 18 



35' E. 

 27 E. 

 42 E. 

 15 E. 

 38 E. 

 18 

 44 



3 

 23 



1 



27 w. 

 48 w. 

 33 w. 

 58 w. 

 45 w. 

 13 w. 



w. 



4 w. 

 20 w. 

 40 w. 

 20 w. 

 12 w. 

 57 w. 

 52 w. 



w. 



w. 



w. 



ve. 



35 w. 



36 Mr. 

 w. 



SO w. 



30 w. 

 11 w. 

 61 w. 



31 w. 



37 w. 



30 w, 



52 w. 

 55 w. 

 55 w. 

 16" w. 



53 w. 

 11 w. 



3 w. 



31 w. 



32 w. 

 32 w. 



29 w. 

 15 w. 



20 w. 



30 w. 



