106 
HINTS TO TRAVELLERS, 
the last station. Take the sheet off the table and fix another on, drawing 
a line npon it in a part most convenient for the work; then cnt the 
sheet just taken off, by the line drawn on it; apply this edge to the line 
on the new sheet, and as they lie in that position, continue the lines from 
the other station on the new paper, and prick through the positions of as 
many stations that have been fixed on the old sheet as yon conveniently 
can. If the positions of three fixed points are thus transferred to the new 
sheet, the place of a new station can be found in the manner shown in 
Figs. 2 or 3 and 4. On each new sheet place the compass, and revolve 
the table until the needle points to north, and then draw a dark line 
which will represent magnetic north, unless the needle is deflected by the 
influence of local attraction. The better plan, if provided with a watch 
and sextant, will be to find the true bearings of some conspicuous 
object, in the manner shown on page 206, and mark it on the table. 
To join the sheets together, and thus form one rough map, place the 
edge of the sheet that has been cut accurately against the line drawm 
on the new sheet, and with the aid of the ruler, see that the line 
projected on the new sheet from the last station (on the sheet that 
has been removed) is an exact continuation of the corresponding line 
on that sheet. 
When a survey has to be made of a considerable tract of country, it 
will be necessary to construct the graticules of a map, including the area, 
with the tables (pp. 67-72), and in the manner there described. Place 
this map on the plane table and mark on it, either by pricking through, 
or by latitude and longitude, positions which have been previously 
approximately fixed by triangulation, or by astronomical observation. 
On one of these positions which promises to give the most extensive 
view of the country to be surveyed the plane table should be set up, and 
oriented, that is, with its meridians as nearly true north and south as 
possible. The best way of doing this will be, if provided with a sextant 
or theodolite, to determine the true bearing of one of the fixed points 
by its angular distance from the sun, in the manner shown pp. 206-207; 
and by placing the edge of the alidade on the spots indicating the posi¬ 
tion of the plane table and the position of the fixed point, the true bearing 
of which has been determined. Turn the table round until the hair in 
the sights covers the fixed point, then, if the map has been properly 
projected and the positions of the fixed points accurately laid down, the 
