LOWEST TEMPERATURE OF JANUARY, 1838. 
243 
Naturalist , some notes on the effects of this extreme cold upon vegetation; at 
present it is impossible to ascertain the injury done to many species whose time 
of growth is not yet come. In my garden hundreds of evergreen shrubs appear 
to be destroyed, unless the main stems or roots may be still alive. 
The paper in the Monthly Chronicle , which has called forth these remarks, is 
occupied with observations on Mr. Murphy’s predictions of the weather, which 
are so frequently altogether erroneous. The fixing the day of lowest temperature 
was certainly a very lucky guess, if a guess only; but there is an explanation 
which I have not seen referred to by his critics. Taking the average of a long 
series of years, the coldest weather of London occurs in the three days following 
the ISdi of January. Hence the probability that the lowest temperature may 
occur on the night between the 19th and 20th. The day of actual greatest cold 
in single years is not uncommonly remote from the 20th of January; although 
in a series of years we shall find that it falls most frequently between the 13th 
and 23rd of January. According to Howard on the Climate of London, first 
edition, in the ten years following 1806, the lowest; temperature occurred seven 
times in January; and six of these seven times were between the 13th and 
23rd; the other being on the 29th. From this and other evidences I am disposed 
to think that Mr. Murphy’s prognostications are partly founded upon the em¬ 
pirical averages from past observations ; that they are predictions a posteriori , 
and not really derived from principles which enable him to determine weather 
a priori. Most enthusiasts in science start from a few ascertained facts; and 
having imagined a theory in correspondence with these facts, they can never be 
wholly destitute of coincidences in favour of their imaginary principles. 
The insertion of these remarks in The Naturalist will have two useful results; 
first, that of correcting an error published on influential authority; and secondly, 
it will show that prognostications of temperature may be made as probabilities , 
without thereby proving the prognosticator to have discovered any new and cer¬ 
tain principles for calculating this beforehand. 
Thames Ditton , Surrey , 
March 4, 1838. 
