Agricultural Meteorology. 
339 
noticed by Sir John Herscliel :* and it apj)cars to be connected 
with another attribute of that phase in the spring; of the year, 
much dreaded in France, and known as the " lune rousse,"t Tliis 
unlucky name is g-iven to the full moon which occurs in the latter 
part of April or the beginning? of May, i. e. during that season 
in which vegetation has sprung up into activity and yet is very 
susceptible; in which the temperature still descends very low at 
night after a hot parching day. This excessive difference between 
the solar radiation "by day and the corresponding terrestrial 
radiation by night is greatly promoted by the clear atmosphere 
which has been suj)posed, with much reason, to characterise the 
few days immediately about the full moon. 
The effect of the moon may be more evident in climates 
where rainy days are comparatively few, and yet imperceptible in 
latitudes like our own, where, owing to other causes, they are 
frequent. The chances of rain are then of course proportionably 
augmented, wholly independent of any real or supposed lunar 
agency. At Lancaster and at Penzance, where it rains IG7 days 
in the year, there is double the probabdity that there is at Mont- 
pellier, yvhich has only 81, or Perpignan, which has 70; and 
more than four times the likelihood tliat it yvill rain compared 
yvith Toulon (40) and Messina {2>7). 
The precise nature of the moon's influence has never been 
exactly sul)Stantiated, though it has been more or less believed in 
old as well as modern times, and in distant countries not deriving 
* See Sir John Herschel's forthcoming work, entitled ' Outlines of As- 
tronomy,' p. 261; and also the Athenaeum for 1836, No. 499, p. 3G0. 
I have been permitted by the kindness of Sir John Herschel to peruse 
extracts from his diaries relating to the character of the weather, observed 
during 80 full moons. The prevalence of a serene unclouded atmosphere, 
while the moon is so nearly full as to appear round to the eye, and is 
actually above the horizon, is very striking — a bright moonlight night 
often intervening between days otherwise consecutively cloudy and wet. 
Supposing this to take place equally in other parts of the temperate zone, 
it would corroborate and explain the diminished tendency to rain, ob- 
served as above, &ince the interval in every day towards that period, in 
which there is a probability of rain, is at once reduced to one half by the 
elimination of all those hours duiing which the moon so 'round to the 
eye' is visible. 
This is of more practical use to the wayfarer than to the agriculturist, 
since the character of the weather by night, as far as his operations 
are concerned, is of less conseqvience than that which occurs by day ; 
though no doubt the liability to frosty nights at particular seasons, which 
accompanies the full moon, may occasionally render it advisable to anti- 
cipate or delay the sowing of certain crops by two or three days, in order 
to avoid the damage of which a particular stage of germination is suscep- 
tible from that cause. 
•(• A full explanation of this circumstance is given by Arago ui the ' An- 
miaire du B. des Longitudes,' 1832. 
