III. The variation of the magnetical compass, observed by Capt. Rogers, Commander of the ship Duke, in his passage from Cape St. Lucar in Calefornia to the Isle of Guam or Guana, one of the ladrones, with some remarks thereon. Communicated by the same

Abstract

Having lately had the Opportunity of perusing Capt. Woods Rogers's origingal Journal, who in 1709-10, in eight Weeks time traversed the great South-Sea , or Pacifick Ocean , I was highly pleased to find the Care he had taken to set down the variations of the Magnetical Compass in his Passage from the South Cape of Calefornia to the Island of Guana , being about seven Horus or 105 Degress of Longitude.