128 



FOREST INFLUENCES. 



The increased rainfall on the forty-eight stations is so considerable that a suffi- 

 cient quantity may without losing significance be ascribed to other local causes, as, 

 for instance, height and form of a mountain range in front or back, etc. Besides, 

 the greater amounts of rainfall at these stations have been used in calculating the 

 averages for the altitude zones, magnifying, therefore, these averages so that the 

 actually observed oue appears really smaller than if the quantities from deforested 

 and forest areas are compared. 



Expressed in percentages of the height of precipitation, an increased rainfall is 

 shown for several localities in very large quantities, which will allow considerable 

 reductions for other influences w^ithout losing their significance for the main proposi- 

 tion. Especially important appears the fact relating to two st-ations near the rain 

 minimum, w^hichalso shows this influence of the forest. 



Lastly, as a matter of interest I may state that the water balance is drawn for the 

 whole Kingdom, which is of special value, because the political boundaries coincide 

 with those of the upper Elbe watershed; therefore it is easy to determine how 

 much of the yearly rainfall is removed by the natural water courses. According to 

 the calculations made for the various zones by addition, the total precipitation 

 upon the area of 51,955.98 square kilometers (about 20,000, square miles) of the 

 Kingdom is found to be 35,398,670 cubic meters, of which the Elbe carries about one- 

 fourth, or 8,849,667 c. m., to the sea. This figure represents a mean rainfall for the 

 whole country of 681 mm., while the mean of observation is 693 mm. 



RESULTS OF OBSERVATIONS IN INDIA AND BRAZU>. 



The following" interestiug observations show the remarkable in- 

 fluence of forest areas in troiiical and subtropical countries (Annual 

 Eeport, 1889). Conditions in India are exhibited in the following table : 



Ivflvence of forest areas on rainfall in India. 



* Mean of two years. 



A glance at this table will show that the presence of ivoodn has a far greater inftuoire 

 in mitigating the tcmperatnre during the hot and dry months of April and Mail than the 

 proximity of the sea. The same is true of the relative humidity, especially at Sibsagar, 

 {. e., in the niiddle'of the forests. Most striking is the effect of the presence of woods in 

 the diminution of the extreme maxima. The greater or less proximity of the sea has but 

 little effect, but as soon as tve reach the wooded region the extreme maximum falls 9 de- 

 grees. Thus in 1875 the maximum thermometer did notrise above 35.3 degrees at 

 Goalpara, while at Lucknow there was not a single day from March 14 to June 22 

 on which a higher temperature had not been observed. The great humidity of the 

 air even during the hot and dry months of April and May is the cause why, in the 

 forests, the raius begin early in March and gradually increase in intensity until 



