NATURAL PHILOSOPHY. 161 



teresting observations were on the return voyage, in March, 1848, in the 

 Hibernia, on account of the high seas, and the peculiar construction of 

 the upper works of the ship, which afforded various platforms of deter- 

 minate elevation above the line of flotation. The first observation was 

 on March 5, in latitude about 51, longitude 38 50' W., the wind be- 

 ing about W. S. W., and the ship's course, true, N. 52 E. The 

 wind had blown a hard gale the previous night, and still continued. 

 Dr. S, took his station on the cuddy roof, the eye being 23 feet 3 inch- 

 es above the line of flotation of the ship, and found that almost every 

 wave rose so much above the level of the eye as to yield only the min- 

 imum elevation, showing that they were most of them more than 24 

 feet high (including depression as well as altitude), or, reckoning from 

 tho mean level of the sea, more than 12 feet. He then went to the 

 larboard paddle-box where the eye was 30 feet 3 inches above the sea, 

 a level which was very satisfactorily maintained during the instants of 

 observation, because of the whole of the ship's length being occupied 

 within the clear " trough of the sea," and in an even and upright po- 

 sition, whilst the nearest approaching wave had its maximum altitude. 

 Here, too, at least half the waves were far above the level of the eye, 

 long ranges extending perhaps 100 yards on one or both sides of the 

 ship (the sea coming nearly right aft), rising so high along the visible 

 horizon as to form an angle estimated at 2 to 3, when the distance 

 of the wave summit was about 100 yards. This would add nearly 13 

 feet to the level of the eye. This amount of elevation was by no 

 means uncommon, and sometimes peaks of crossing, or crests of break- 

 ing seas, would shoot upwards at least 10 or 15 feet higher. The aver- 

 age wave was fully 15 feet or upwards, and the mean highest waves, 

 not including the broken crests, about 43 feet above the level of the 

 hollow occupied at that moment by the ship. The next day, after a 

 storm of about 36 hours, which had abated several hours before the ob- 

 servation, so that the waves had perceptibly subsided, waves were 

 noticed of 26 feet average elevation from ridge to hollow, and even of 

 30 feet ; they were, however, of no great extent on the ridge. 



At this time another subject -of investigation was the period of the 

 regular waves overtaking the ship, and the determination, proximately, 

 of their actual width or intervals, and their velocity. The period of 

 regular waves, in incidental series, overtaking the ship was, on the 

 average, 16". 5. A wave passed the length of the ship, 220 feet, in 

 about six seconds, and an estimate gives 559 feet as the probable mean 

 distance of the waves, or the width passed over between crest and crest. 

 To this, however, an addition must be made, on account of the pro- 

 gression of the ship in the same direction, of 231.5 feet, giving 790.5 

 feet for the actual distance traversed by the wave in 16.5 seconds of 

 time, being at the rate of 32.67 English statute miles per hour. Of 

 the elements employed in this calculation, all but one may be deemed 

 accurate, the doubtful one being the average distance from summit to 

 summit of the waves ; and even this must be very nearly correct. As 

 to the form of the waves, it was found that it was less regular during 

 the height of the gale than after the wind had begun to subside. 

 London Athenaeum, Aug. 



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