be sufficient to explain the operations directed in the above general rule.

EXAMPLE.

112. April 27th, 1852, at noon. A point of land in latitude 36° 30' S. and longitude 110° 20' W. bore by compass E.N.E.E. (ship's head being S. E. by S. by compass), distant 14 miles; afterwards sailed as by the following log account; required the latitude and longitude in, on April 28th, at noon.

(1.) The column in the above table headed deviation should be formed from the general table of deviations (p. 16) previously to correcting courses. Thus, in the first course in the preceding table, the ship's head is S.W. W.; looking in the deviation table we see that the corresponding correction is W. or 1. (Rule i.)

(2.) Form a table such as below, by writing down the headings, points, courses, &c., over the seven columns which are to be filled in with the corrected courses, &c.

N.

The courses are more readily corrected by drawing two lines at right angles, to represent the N., S., E., and W. points of the compass, and then a line to represent (roughly) the compass course of the ship. The direction in which the correction for leeway must be applied will then be easily seen.

After some experience in correcting courses, they can

W.

3

D.

C

S.

be made mentally, and the diagram dispensed with.

To correct the departure course which is W.S.W.W. (the opposite bearing to E.N.E.E.).

Draw a line roughly in the fig. W.S.W.W. as Cl; it is

or 7 pts. 3 qrs. left of N., or W. N. dist. 14'. Insert this course and distance in table below.

First Course.-S.W.W.

Draw a line in fig. S.W.W. as C2; then

The distance 8.2' is found by adding up the hourly distances until the course is altered, at 4 o'clock. Insert this course and distance in the table.

Second Course.-W.b. S. 1S.

Draw a line in fig. W.b.S. S. as C3.

Third Course.-W.b.N.N.

Draw a line W.b.N.N. as C4.

or N.W.b.N.W. 23.6'.

Insert this course and distance in table.

Fourth Course.-N.W.W.

Draw a line N.W.W. as C5.

Proceed with the 5th and 6th courses in the same manner,

Previously to opening the traverse table to take out the difference latitude and departure corresponding to each course and distance in the above table, fill up the columns not wanted: thus in the first course W. N. the N. and W. columns will be wanted; fill up the S. and E. columns by drawing a line under S. and E. In the second course W. the three columns N., S., and E., will not be wanted; fill them up with lines. In the same manner proceed with the other courses.

(4.) To find difference latitude and departure for each course and distance, by traverse table.

Enter traverse table, and take out the difference latitude and departure corresponding to 73 points, and distance 140.