Page:Proceedings of the Royal Society of London Vol 69.djvu/91

when the planetary effect reaches its maximum. Drawing then the line AC corresponding to a maximum on June 21, we know that the sea effect cannot exceed BC in magnitude, and that the effect which is independent of the sea, cannot be less than AC.

Fig. i is a scale drawing representing this analysis of the temperature oscillation for Kew into two parts. It will be noticed in Table II that the sea temperature reaches its maximum at the Shetlands, at Scilly, and at Yarmouth on from August 10 to 13. Taking August 12 as a mean date, the sea effect reaches its maximum 20 days after the maximum of the first-order curve at Kew ; the line BC is therefore ruled at 20 to AB. AC, being unknown, is dotted at an angle of 32, corresponding to 32 days, the lag of the time of maximum at Kew behind the solstice (June 21). It follows from the measure- ments of the diagram that the sea effect at Kew cannot exceed 8 0< 3 F., and the original effect, apart from sea, cannot be less than 5*3 F.

The mean amplitude of the sea variation is nearly 8 D F., so that if the lag of the seasons at Kew is wholly due to the sea, the whole variation of temperature of the sea is superposed upon the initial variation. This would no doubt be an exaggeration, and the initial variation at Kesv must be greater than the 5'3 F. shown in the diagram.

A corresponding diagram drawn for Scilly from the air and sea temperatures there (fig. ii)- represents nearly the whole temperature

FIG. ii.