If these opinions respecting lunar influence were limited to particular countries, they would be less 
entitled to serious consideration ; but it is a curious fact that many of them prevail and have prevailed in 
quarters of the earth so distant and unconnected, that it is difficult to imagine the same error to have pro- 
ceeded from the same source. At all events, the extent of their prevalence alone rendered them a fit sub- 
ject for serious investigation and I propose at present to lay before you some of the principal facts and argu- 
ments bearing on these points, for the collection of which we are mainly indebted to the industry and 
research of M. Arago. 
A large volume would be necessary to analyze all the popular opinions which refer to the supposed 
lunar influences. We shall confine ourselves therefore to the principal of them, and shortly examine how 
far they can be reconciled with the established principles of astronomy and physics. 
The Red Moon . — It is believed generally, especially in the neighbourhood of Paris, that in certain 
months of the year, the moon exerts a great influence upon the phenomena of vegetation. Gardeners give 
the name of Red Moon to that moon which is full between the middle of April and the close of May. Ac- 
cording to them, the light of the moon at that season exercises an injurious influence upon the young shoots 
of plants. They say that when the sky is clear, the leaves and buds exposed to the lunar light redden and 
are killed as if by frost, at a time when the thermometer exposed to the atmosphere stands at many degrees 
above the freezing point. They say also that if a clouded sky intercepts the moon’s light, it prevents these in- 
jurious consequences to the plants, although the circumstances of temperature are the same in both cases. 
Any person who is acquainted with the beautiful theory of dew, which we owe to Dr. Wells, will find 
no difficulty in accounting for these effects, erroneously imputed to the moon. If the heavens be clear and 
unclouded, all substances on the surface of the earth which are strong and powerful radiators of heat, lose 
temperature by radiation, while the unclouded sky returns no heat to them to restore what they have lost. 
Such bodies, therefore, under these circumstances, become colder than the surrounding air, and may even, 
if they be liquid, be frozen. Ice, in fact, is produced, in the warm climates, by similar means. But if the 
firmament be enveloped in clouds, the clouds, having the quality of radiating heat, will restore by their ra- 
diation, to substances upon the surface of the earth, as much heat as such substances lose by radiation; the 
temperature, therefore, of such bodies will be maintained at a point equal to that of the air surrounding them. 
Now the leaves and flowers of plants are strong and powerful radiators of heat ; when the sky is clear 
they therefore lose temperature and may be frozen ; if, on the other hand, the sky be clouded, their tem- 
perature is maintained for the reasons above stated. 
The moon, therefore, has no connection whatever with this effect ; and it is certain that plants would 
suffer under the same circumstances, whether the moon is above or below the horizon. It equally is quite 
true that if the moon is above the horizon, the plants cannot suffer unless it be visible, because a clear sky 
is indispensable as much to the production of the injury to the plants as to the visibility of the moon ; and, 
on the other hand, the same clouds which veil the moon and intercept her light give back to the plants 
that warmth which prevents the injury here adverted to. The popular opinion is therefore right as to the 
effect , but wrong as to the cause ; and its error will be at once discovered by showing that on a clear night, 
when the moon is new, and therefore not visible, the plants may nevertheless suffer. 
Time for felling Timber . — There is an opinion generally entertained that timber should be felled only 
during the decline of the moon ; for if it be cut down during its increase, it will not be of a good or durable 
quality. This impression prevails in various countries. It is acted upon in England, and is made the 
ground of legislation in France. The forest laws of the latter country interdict the cutting of timber during 
the increase of the moon. M. Auguste de Saint Hiliare states that he found the same opinion prevalent in 
Brazil. Signor Francisco Pinto, an eminent agriculturist in the province of Espirito Santo, assured him, as 
the result of his experience, that the wood which was not felled at the full of the moon was immediately attacked 
by worms, and very soon rotted. 
In the extensive forests of Germany, the same opinion is entertained and acted upon with the most un- 
doubting confidence in its truth. Sauer, a superintendent of one of these districts, assigns what he believes 
to be its physical cause. According to him, the increase of the moon causes the sap to ascend in the tim- 
ber : and, on the other hand the decrease of the moon causes its descent. If the timber, therefore, be cut 
during the decrease of the moon, it will be cut in a dry state, the sap having retired ; and the wood, there- 
fore, will be compact, solid, and durable. But if it be cut during the increase of the moon, it will be felled 
with the sap in it, and will therefore be more spongy, more easily attacked by worms, more difficult to season, 
and more readily split and warped by changes of temperature. 
Admitting for a moment the reality of this supposition concerning the motion of the sap, it would 
follow that the proper time for felling the timber would be the new moon, that being the epoch at which the 
descent of the sap would have been made, and the ascent not yet commenced. But can there be imagined 
in the whole range of natural science, a physical relation more extraordinary and unaccountable than this 
supposed correspondence between the movement of the sap and the phases of the moon ? Assuredly theory 
affords not the slightest countenance to such a supposition ; but let us inquire' as to the fact whether it be 
really the case that the quality of timber depends upon the state of the moon at the time it is felled. 
