______|______________________|

The intervals between the ascending and descending passages of the
different vortices, are

Between I. A. and I. D. from 11 to 14 days.
" O. A. " O. D. " 10 " 12 "
" C. A. " C. D. " 9 " 11 "

and the effect is greatest when the vortex comes to the meridian before
the sun, and least when after the sun; in which case the full effect is
not developed, sometimes until the following day.

A brief abstract from a journal of the weather for one sidereal period
of the moon, in 1853.

_June_ 21st. Fine clear morning (S. fresh)[15]: noon very warm 88d;
4 P.M. plumous _cirri in south_; ends clear.

22d. Hazy morning (S. very fresh) arch of cirrus in west; 2 P.M., black
in W.-N.-W.; 3 P.M., overcast and rainy; 4 P.M., a heavy gust from
south; 4.30 P.M., blowing furiously (S. by W.); 5 P.M., tremendous
squall, uprooting trees and scattering chimneys; 6 P.M., more moderate
(W.)

23d. Clearing up (N.-W.); 8 A.M., quite clear; 11 A.M., bands of mottled
cirri pointing N.-E. and S.-W.; ends cold (W. N.-W.); the cirri seem to
rotate from left to right, or with the sun.

24th. Fine clear cool day, begins and ends (N.-W.)

25th. Clear morning (N.-W, light); 2 P.M. (E.) calm; tufts of tangled
cirri in north intermixed with radiating streaks, all passing eastward;
ends clear.

26th. Hazy morning (S.-E) cloudy; noon, a heavy windy looking bank in
north (S. fresh), with dense cirrus fringe above on its upper edge;
clear in S.

27th. Clear, warm, (W.); bank in north; noon bank covered all the
northern sky, and fresh breeze; 10 P.M., a few flashes to the northward.

28th. Uniform dense cirro-stratus, (S. fresh); noon showers all round;
2 P.M., a heavy squall of wind, with thunder and rain (S.-W. to N.-W.);
8 P.M., a line of heavy cumuli in south; 8.30 P.M., a very bright and
high cumulus in S.-W., protruding through a layer of dark stratus;
8.50 P.M., the cloud bearing E. by S., with three rays of electric
light.[16]

[Illustration: Fig. 17]

_June_ 29th. A stationary stratus over all, (S.-W. light); clear at
night, but distant lightning in S.

30th. Stratus clouds (N.-E. almost calm); 8 A.M., raining gently;
3 P.M., stratus passing off to S; 8 P.M., clear, pleasant.

_July_ 1st. Fine and clear; 8 A.M., cirrus in sheets, curls, wisps, and
gauzy wreathes, with patches beneath of darker shade, all nearly
motionless; close and warm (N.-E.); a long, low bank of h