64 NOTES ON THE PROLONGED FROST, 1890-91.
which he bequeathed to the Royal College of Physicians, all perished
in the Great Fire in 1666. Almost equally sad is it that his portrait,
painted in oils, —which he himself presented to the Schools' Gallery
of Oxford, has disappeared. It is believed to have been destroyed
as rubbish forty years ago. Only a steel engraving, made in 1796,
which differs from the original picture in several details, remains to
witness to the scholarly features of the great doctor. The engraving
in reproduced in the plate (frontispiece to the volume), which
accompanies this paper.
His residence in Colchester still stands, and his tomb in the
church of Holy Trinity still proclaims over his ashes the virtues
which he practised whilst living.3 But his memorial remains in bis
magnetic and electrical discoveries. His reputation is enshrined in
the science which he founded —" shining in an eternal sepulchre."
NOTES ON THE RECENT PROLONGED FROST,
1890-91.
By JOHN C. THRESH, D.Sc., M.B., F.R.,Met.Soc, etc.
[Read March 21st, 1891.]
THE following brief notes upon the recent prolonged frost are based upon the
daily observations taken at the Climatological Station, Chelmsford, which
is in my charge.
For the last few days in November and the first two days in December the mean
temperature was below freezing point and about five inches of snow fell. From
the 3rd to the 9th December the mean daily temperature was above 32° F. and all
the snow rapidly disappeared. The prolonged frost set in on the 10th, when the
mean temperature fell below freezing point and remained constantly below until
January 13th, that is, for a period of thirty-three days. On the latter date the
temperature rose to 33.9 and remained over 32° until the 16th. It then fell
and remained low until the 20th, when it again rose and the thaw set in. With
this slight intermission, therefore, the frost lasted forty-one days, or one day only
short of six weeks.
The coldest day was December 22nd. On this day the minimum temperature
was 4.3, the maximum 30.5. At 9 a.m. the thermometer stood at 7'9. The mean
temperature for the day was only 17.4. The subjoined chart is interesting as
showing at a glance the minimum temperature and the mean daily temperature
throughout the whole period of frost.
Snow fell on eleven days. The heaviest fall was on December 18th, when a
depth of three inches was registered. The snow attained its greatest depth on
the 30th, where there was between five and six inches on the ground. On January
20th rain fell ('27 in.) the temperature rose and the snow disappeared. The total
3 The best drawing and description of the tomb, with its numerous coats of arms, and some
account of Gilbert's family, will be found in Chancellors "Ancient Sepulchral Monuments of
Essex," pp. 202-6, pl. lxvii.—Ed.