WCP1759

[1]

9, St. Mark's Crescent

Regent's Park N.W.

Dec^r 11th [unknown]

Dear Griffiths¹ [sic]

Can you or any of your mathematical masters explain to me the following difficulty:

[sketch of Earth at two different points on a curve A to B, with directional arrows and points of reference labelled a, b, and c.]

In the above figure the Earth moves in its orbit from A to B at the rate of about 65.800 miles an hour.

But the Earth is at the same time revolving on its axis at about 1.040 miles an hour, at the Equator.

[illeg.] point a. will therefore, at midnight, be moving 65.800 + 1040 = 66.840 miles an hour.

And at noon 65.800 — 1040 = 64.760 miles an hour or nearly 1/30 quicker at midnight than at noon. What becomes of the vis viva of the earth and ocean each 12 hours? Must [2] it not cause a tidal wave about the points b. and c. where the loss and gain of motion are greatest?

I cannot find this alluded to in any account of the tides or of the dynamical effects of the Earth's motions.

These are anomalies in the tides hitherto unexplained — may not this constant diurnal tide help to explain them?

The obliquity of the ecliptic will of course complicate and somewhat diminish the effects, but [3] not I think materially.

Please let me know if I have found a mare's nest as I am no mathematician.

Yours very sincerely, | Alfred R. Wallace [signature]