134 
HINTS TO TRAVELLERS. 
meridian, and by using this station (B) as one end of his base, and drawing 
rays on his plane table through the points from which rays were drawn at 
A, making a sketch map of the country through which he has passed. In 
order to do this he must ascend B, and take observation by north and south 
stars for latitude. The mean of results so obtained ought to be very near 
the truth. Suppose, in the present instance, that the latitude so found was 
5° N., then by placing the straight edge on that latitude on each side of 
the graduated meridians, and drawing a line between those two points, 
its intersection with the line of true bearing of B drawn from A, will be 
the place of B on the map. Again, placing the straight edge on the point 
of intersection of this parallel of latitude and the line of true bearing of 
B from A, and then moving it until it is parallel with the graduated 
meridian, it will cut the graduated parallel in the longitude of B, which 
in this case is 30° E. Knowing the latitude and longitude of B, the error 
of the watch on the reference meridian can be found by the methods given, 
pp. 153,160, 162. 
The weak point in this system of surveying is, that it cannot bo 
employed when the direction of the line of route approaches east or 
west, as the angle between the parallel of latitude and the line of bearing 
would be too acute to give satisfactory results. 
