assist in determining their limits cannot fail to be acceptable. The inquiry is, first, as to the height of the solid wave above the mean water level. Secondly, the distance of the ridges apart. Thirdly, the rate at which the wave travels, and whether the height and distance of the ridges vary with the velocity. Fourthly, what is the greatest estimated extent of any one of those ridges.

The most simple way of measuring the height is, when the vessel is in the lowest part of the trough between two following seas, to ascend the rigging to such a height as will bring the top of the wave on with the horizon, to put a mark, note the inclination of the vessel, and at leisure to measure the perpendicular height of the eye above the water line, which we may presume will be double the height of the wave above the mean water level. It will necessarily require several observations to be made before any satisfactory conclusion can be arrived at. The distance of the waves apart may possibly be tested by actual measurement, by means of the lead-line and a float veered out to such a distance that the float shall be on the crest of one wave when the ship is on the top of the other. And the rate may be determined by the time occupied by the wave in passing from the float to the ship: the rate of the ship through the water and the angle her course makes with the route of the wave being known. There are other methods of determining this interesting problem which will no doubt occur to the intelligent observer, and they are sufficiently numerous to afford ample exercise of his ingenuity, but all are attended with difficulty, owing to the circumstances under which the observations are required to be made.

APPENDIX No. 1.

Remarks upon the Currents which prevailed in the passage across the Atlantic.

"From the time we quitted Teneriffe, with the N. E. trade-wind, until we lost the breeze in lat. 7° 40' N., long. 260 40' W., the current set on an
average S 540 W. true, at the rate of 11 miles per day. On losing the trade and entering the calm latitudes, the westerly current ceased, and the
next 24 hours the ship was set N. 830 E. true 23 miles. The meeting of the opposite currents was marked by a strong ripple, which was traced to a
considerable distance. The four succeeding days, in which we changed our position from lat. 7° 20' N., and long. 26 58' W., to lat. 30 56' N.,
long. 26° 44' W., the current ran S. 700 E. true 13 miles per day. Here we met the S.E. trade, and with it experienced a strong current, which
carried us N. 620 W. true 23 miles per day, until we made Fernando Norhona. Hence to a position 100 miles due E. of Cape Ledo the current set
between S. 780 W. and S. 210 W. (true) on an average daily rate of 27 miles." &c.

"While in Rio Janeiro H.M. ships A. and B., the packet C., and a fast-sailing schooner the D. arrived, and we learnt that the A. had crossed the
equator in 180 W., the B. in 250 W., the C. in 2940 W., the D. in 390 W., whilst we crossed in the E. in 300 W.; and upon inquiry it appeared that
the passages from England were as follows, viz.: the A. was 49 days, B. 40 days, C. 38 days, the E. 36 days, and the D. 110 days, having got so far
to the westward that she could not weather Cape St. Roque, and was obliged to stand back to the variable winds to regain her easting. Thus it appears
that, with the exception of the D., the passages were shortened in proportion as the equator was crossed to the westward," &c. &c.