EESULTS OF COMPARATIVE OBSERVATIONS: FRANCE. 



263 



from differences of forests the amount of rain was reduced but 12 to 13 

 per cent. 



Observations for determining the effect of woodlands upon the climate 

 are also made at the experimental station and School of Forest Guards 

 at Barres, the results being reported to the general office of the service, 

 and to the observatory at Mount-souris. 



Observations tipon the rain-fall made under the direction of the Marshal 



Vaillant. 



In 1866, two series of observations were made upon eight rain-gauges 

 in the Crown forests of Fontainebleau and Gonards, with the view 

 of determining the influence of a covering of woodland upon the amount 

 of rain reaching the earth. There were four gauges at each place, 

 of which one was exposed freely to the open air, and the remaining 

 three under woods of different kinds. These observations were pub- 

 lished in the Bevwe des Eaux et Forets, and in the Atlas Meteorologique of 

 the Imperial Observatory of Paris for 1867. Instead of giving the actual 

 rain-fall in the woods we give the difference between this and the amount 

 falling in an open space, as this element is the one of chief importance 

 in these studies : 



Rainfall in open fields and in woods. (Millimeters.) 



* The rain-gange at Gonards was not established nntil February 23. The marshal expressed an in- 

 tention of establishing two other sets of observations, but we are not aware that this was done. 



Coinparative observations of M. Fautrat. 



This observer has communicated on several occasions to the Academy 

 of Sciences at Paris, the results of comparative observations made by 

 him at stations 8 kilometers apart, and as follows: 



Deciduous forest of Hallette, France, 108 meters above tide. 

 Scotch-pine forest of Ermenonville, 92 meters above tide. 



So far as we have met with these records they extend, when combined, 

 over a period from June, 1875, to October, 1877, giving in all two entire 



