« ΠροηγούμενηΣυνέχεια »
At station 5, the meridian distance
5.78 E. 7.76 W.
The next meridian distance
At station 11, the meridian distance 0.12 W.
The next meridian distance
PL 10. fig. 3.
In the 5th and 11th stations, the meridian distance being less than the departures, and of a contrary name, the map will cross the first meridian, and will pass as in the 5th line, from the east to the west line of the meridian ; and in the 11th line it will again cross from the east to the west side, which will evidently appear, if the field-work be protracted, and the meridian line passing through the first station, be drawn through the map,
The field-book cast up by the first method, will be evident from the two foregoing theorems, and therefore requires no further explanation ; but to find the area, by the second method, take this
When the meridian distances are east, put the products of north and south areas in their proper columns; but when west, in their contrary columns ; that is, in the column of south area, when the dif. ference of latitude is north; and in north when south : the reason of which is plain, from the two last tlieorems. The difference of these two columns will be the area of the map,
8 NW 53 11.60
9 NE 36
10 NE 22
N 3.54 6.61 E
14.00 E 2.68 5.96 W
S 1.21 7.75 W
12 SW 15 10.85
13 SW 163 10.12
S 10.48 4.32 E
S 9.69 1.46 E;
Content in chains, 1107.05131
It is needless here to insert the columns of bearing or distances
in chains, they being the same as before.
No. Lat. and Merid.
N. Area. S. Area
N 3.54! 6.61 E
23.3994 E 6.61 |13.22 E
N 9.65 15.02 E 2
144.9430 E 1.80 16.82 E
E 8.10 33.02 E
178.0499 Area in chains, as before, 1107.0513
Construction of the Man from either the 1st or the 2d Table.
PL. 10. fig. 3.
Draw the line NS for a north and south line, which call the first meridian; in this line assume any point, as 1, for the first station.
Set the northing of that stationary line, which is 3.54, from I to 2, on the said meridian line. Upon the point 2 raise a perpendicular to the eastward, the meridian distance being easterly, and upon it set 13.22, the second number in the column of meridian distance from 2 to 2, and draw the line 1 2, for the first distance line : from 2 upon the first meridian, set the northing of the second stationary line, that is, 9.65 to 3, and on the point 3 erect a perpendicular eastward, upon which let the meridian distance of the second station 16.82, from 3 to 3, and draw the line 23, for the distance line of the second station. And since the third station has neither northing nor southing, set the meridian distance of it 33.02, from 3 to 4, for the distance line of the third station. To the fourth station there is 29.44, southing, which set from 3 to 5; upon the point 5, erect the . perpendicular 55; on which lay 13.54, and draw the line 4 to 5.
In the like manner proceed to set the northings and southings on the first meridian, and the meridian distances upon the perpendiculars raised to the east or west; the extremities of which connected by right lines, will complete the map.