Use of the table.—Find the required parallel, the tens at the side and the units at the top, at their intersection will be found a quantity, which, multiplied by the departure, gives the difference of longitude.

The departure from the meridian on the parallel of 34° was 25 miles, required the difference of longitude:

25´ × 1·20 = 30·00´ the difference of longitude.

In the parallel of 60° the departure was 30 miles:

30´ × 2 = 60 miles, or 1 degree.

In the parallel of 35° N. the route was N. 40° W. 37 miles distance.

By traverse table, 40° course, dist. 37° = dep. 23·8´ × 1·22 = 29·03 miles difference of longitude.

The following example will serve to show how the traveller’s record of progress may be conveniently kept. It was framed by S. W. Norie expressly for the use of navigators; but explorers and travellers will find it a simple and useful form for recording the day’s work:

Corrected
Courses		Distance.Difference of Latitude.Departure.
N.S.E.W.
N.E.3625·5 25·5
N. by W.1413·7 2·7
N.E. by E. ½ E.5827·3 51·2
N. by E.4241·2 8·2
E.N.E.2911·1 26·8
Difference of Lat.118·8 111·72·7
2·7
Dep.109·0

The difference of latitude 118·8 and departure 109·0 give the course N. 42° 32´ E., and distance 161·2.