Page:TASJ-1-1-2.djvu/96

 to give it a tendency in that direction, because of the atmospheric pressure being so much greater on the outside than on the inside.

By reference to the Diagram, we find the Francis Henty entering the typhoon in N.E. by E. quarter, or having the wind S.E. by S. and follow her through the first half of the storm-disc to the centre, the wind having changed but one point to S.E. This change of wind is the effect of having changed the bearing of a centre, first by running to the Northward and Eastward on a course inclining towards the track of the typhoon; and secondly, by heaving to and drifting to the Northward and Westward. Run and Drift together during 11$1⁄2$ hours, making good a course and distance N. 7° 55′ E. 68.5 miles—on the line marked D.R.1., and following her from the centre out, we find that she is drifting to the Eastward, making good a course and distance S. 83° 24′ E. 44.37 miles, on the line marked D.R. 2: but at the end of the Typhoon, the Captain discovered the Macedonian Rocks, 7 miles to leeward, bearing S.S.W. $3⁄4$ W. and 71 miles S. 52° W. of the point where his reckoning placed him. This indicates a strong current having affected the drift of the ship during the gale, at the rate of 3.24 miles per hour, S. 52° W. or S.W. $5⁄8$ W. Applying this current to the course, through the first half of the storm-disc, we shall find that the ship travelled, through the storm-disc, on the straight line marked 1, 2, 3, 4, 5 and 6., and that her track over the ground was on the broken line having the corresponding marks; also that her course through the last half of the storm-disk, lies on the straight line marked a, b, c, d, and e, and that her actual drift over the ground is indicated by the curved line similarly marked.

Diameter of the storm-disc, 360 miles, and rate of travelling 16 miles per hour, N.E. Diameter computed from the time required for the Francis Henty to pass through the storm-disc, and the rate of travelling obtained by having the bearing and distance of the centre from two known points, at different times, and the elapsed time during the interval.