388 VARIATION OP THE COMPASS. 



been pre- When I armed in that island, upwards of twenty-fire 

 »crvcd. years since, I became acquainted with the oldest surveyors 



there, who had practised from thirty to forty years. 

 They had the original papers, field notes, and diagrams 

 of their predecessors, up to the dates of the first surveys. 

 Many of these original papers, field notes, and diagrams 

 are now in my possession ; from which the practice of 

 surveying, taking field notes, and delineating them on 

 diagrams, is clearly shown. 

 The original Jamaica was early divided into counties and parishes, 

 division of Ja- ^he boundary lines whereof were defined by the legisla- 

 counties and ture, and the lines of many marked on earth. In the 

 parishes was county of Surrey, the line, dividing the parishes of Port- 

 pSs\nd th™" ^^^^ ^^^ ^*' C^^orge, is a north and south line, by law, 

 compass still and was marked on earth according to the magnetical 

 agrees with it. nee(ii^, Jt continues in the same direction. In the 

 county of Cornwall, the dividing line between the 

 parishes of St. James and Trelawney continues a north 

 and south line, on earth, as it was first run by the mag- 

 netical needle. This will be evident on the inspection of 

 my maps of Jamaica, lately published. It became neces- 

 sary, in giving the island its true position on the globe, 

 to ascertain its latitude and longitude ; and also the true 

 meridian, with the quantity of the variation of the mag- 

 netical meridian from it. But I have applied these meri- 

 dians diiferently in the maps of the counties, and in that 

 of the island. In the former, in which the situation on 

 the globe is not given, the magnetical is laid down as the 

 principal meridian ; because all surveys of every other 

 description, as well as those of the boundary lines of 

 counties and parishes, are regulated by it ; and the true 

 meridian is introduced only to shew the variation ; but, 

 in the latter, in which its place on the globe is fixed, as to 

 latitude and longitude, the true meridian becomes the 

 principal one ; and the magnetical meridian shows the 

 quantity of variation from it, and regulates the surveys, 

 and the relative situation of places, as in the county 

 maps. 



When Sir Henry Moore, (who was considered a great 

 under'^r He«- surveyor,) was governor of Jamaica, about the year 1760, 

 ry Moore, in maps of that island were constructed, under his imme, 



diata 



