354 Mr. Robertson’s Observations on the Permanency 
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 deli- 
neating them on diagrams, is clearly shown. 
Jamaica was early divided into counties and parishes, the 
boundary lines whereof were defined by the legislature, and 
the lines of many marked on earth. In the county of Surrey, 
the line, dividing the parishes of Portland and St. George, is 
a north and south line, by law, and was marked on earth 
according to the magnetical needle. It continues in the same 
direction. In the county of Cornwall, the dividing line be- 
tween the parishes of St. James and Trelawney continues a 
north and south line, on earth, as it was first run by the mag- 
tietical needle. This will be evident on the inspection of my 
maps of Jamaica, lately published. It became necessary, 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 magnetical meridian from it. 
But I have applied these meridians differently 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 show 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. 
