Mr. H. Harrisse, in his very learned and able critical essay, Fernand Colomb, sa Vie et ses Oeuvres, Paris, 1872, has made it at least extremely probable that the Historie is a spurious work. The compiler may have found this observation in some of the writings of Columbus now lost, but however that may be, the fact, which Humboldt mentions in Cosmos with much interest, still remains, that the doctrine in question was held, if not by the great discoverer himself, at least by one of his pretended biographers, as early as the year 1571.] The effect of the forest on precipitation, then, is by no means free from doubt, and we cannot positively affirm that the total annual quantity of rain is even locally diminished or increased by the destruction of the woods, though both theoretical considerations and the balance of testimony strongly favor the opinion that more rain falls in wooded than in open countries. One important conclusion, at least, upon the meteorological influence of forests is certain and undisputed: the proposition, namely, that, within their own limits, and near their own borders, they maintain a more uniform degree of humidity in the atmosphere than is observed in cleared grounds. Scarcely less can it be questioned that they tend to promote the frequency of showers, and, if they do not augment the amount of precipitation, they probably equalize its distribution through the different seasons. [Footnote: The strongest direct evidence which I am able to refer to in support of the proposition that the woods produce even a local augmentation of precipitation is furnished by the observations of Mathieu, sub-director of the Forest-School at Nancy. His pluviometrical measurements, continued for three years, 1866-1868, show that during that period the annual mean of rain-fall in the centre of the wooded district of Cinq-Tranchees, at Belle Fontaine on the borders of the forest, and at Amance, in an open cultivated territory in the same vicinity, was respectively as the numbers 1,000, 957, and 853. The alleged augmentation of rain-fall in Lower Egypt, in consequence of large plantations by Mehemet Ali, is very frequently appealed to as a proof of this influence of the forest, and this case has become a regular common-place in all discussions of the question. It is, however, open to the same objection as the alleged instances of the diminution of precipitation in consequence of the felling of the forest.