mn 3.2, and in winter
1.6. The duration is least in December and greatest in May; the sun
shining for rather more than an hour a day in December and nearly six
hours and a half in May. An apparent discrepancy between this and the
preceding section is due to a bright day often following a cloudy
morning and _vice versa_.

5. _Wind._--The prevailing direction of the wind, as recorded at
Berkhampstead, St. Albans and Bennington, is from S.W. (sixty-one days
in the year) to W. (sixty-two days), and the next most frequent winds
are N. to N.E. and S. (each about thirty-seven days). The least frequent
are S.E. (twenty-five days). About forty-four days in the year are
recorded as calm.

6. _Rainfall._--Twelve years is much too short a period to give a
trustworthy mean for such a variable element of climate as rainfall, and
five stations are much too few to deduce an average from for
Hertfordshire. The average rainfall at a varying number of stations for
the sixty years 1840 to 1899 (from one station in the first decade of
this period to twenty stations in the last decade) was 26.15 inches. In
the driest year (1854) 17.67 inches fell, and in the wettest (1852)
37.57 inches. Spring has 5.40 inches, summer 6.97, autumn 7.87, and
winter 5.91. The driest months are February and March, each with a mean
of 1.65 inch; April is but very little wetter, having 1.69. The wettest
month is October, with 2.96 inches, and the next is November with 2.56.
The mean number of days of rain in the year, that is of days on which at
least 0.01 inch fell, for the thirty years 1870-99, was 167. Autumn and
winter have each about six more wet days than spring and summer. The
rainfall is greatly affected by the form of the ground, the southern and
western hills attracting the rain, which chiefly comes from the S.W., so
greatly that with a mean annual fall of about 26 inches there is a
difference of 31/2 inches between that of the river-basin of the Colne on
the W. and that of the river-basin of the Lea on the E., the former
having 28 inches and the latter 241/2. The small portion of the
river-basin of the Great Ouse which is within our area has rather less
rain than the average for the county.

IV. FLORA AND FAUNA

In his _Cybele Britannica_, H. C. Watson divided Britain into eighteen
botanical provinces of which the Thames and the Ouse occupy the whole of
the S.E. of England. The greater part of Hertfordshire is in the Thames
province and a small p