1869.] 3Ieteorology. 447 



noticed in Provence that a hedge two metres in height shelters a 

 space 22 m. in width from the effects of the " mistral." Lastly, 

 trees have a decided influence on health, in protecting a district 

 from unwholesome exhalations. It is found along the edge of the 

 Pontine marshes that the existence of a belt of wood is sufficient to 

 ensm'e immunity from malaria to the peasants who live behind it. 

 These then are the most obvious beneficial efiects on climate of the 

 presence of forests in a country. As regards the direct mfluenee 

 of vegetation on the temperature and the climate generally, the 

 author gives the notes of some experiments which he has made on 

 growing trees, in order to determine their temperature and that of 

 the surrounding air at different times of the day. The results seem 

 to show that trees behave as if they were dead or inorganic bodies, 

 receiving heat from external sources and radiating it to surrounding 

 objects. The heat developed in the process of growth was found to 

 be quite inappreciable by means of the instruments employed, while 

 the coohng influence usually assigned to foliage, owing to the 

 constant evaporation going on from its surface, was shown to be 

 utterly unfounded. However, this part of the paper is quite in- 

 complete, as M. Becquerel reserves the exact account of his inquiry 

 for a futiu'e essay. He distinctly denies the truth of the change 

 of climate alleged to have taken place in various countries, and 

 attributed to the clearing of the land, without, as it seems to us, 

 investigating the question thoroughly. 



The ultimate conclusions stated in the paper are, as we have said 

 before, unsatisfactory ; e. g. we are told that the effect of cutting 

 away the forests is to diminish the quantity of runnmg water in 

 the country, but the comparison of observations of rainfall in a 

 district, before and after the clearing, have most decidedly not led 

 to the conclusion that the amount of rain which falls is seriously 

 affected by the clearing. We do not therefore learn to what 

 action the reduction of the amount of river water is to be attri- 

 buted. 



On the whole the paper may be fahly compared to Darwin's 

 first work ' On the Origin of Species.' Both works contain many 

 facts of great interest which have a certain relation one to another, 

 while the reasoning which should bind the whole together is for 

 the most part entirely wanting. We hope that M. Becquerel's 

 promised paper will be more conclusive than this one. 



Before we leave the subject of meteorology in France, we 

 should say that it appears from the Bulletin Hebdomadahe of the 

 Association Scientifique, that the plan for the establishment of a 

 central Physical Observatory in Paris and the proposed modifica- 

 tions in the management of the Observatoire Imperial, the result 

 of which would have been to put a stop to all but the astronomical 

 work carried on there, have both been brought to an end. M. Le 



