PHYSICAL AND METEOROLOGICAL RESEARCHES. 



211 



except during 1 698. Other periods of observations extended from 1773 

 to 1797 and from 1804 to 1872. After January 1, 1873, tlie observa- 

 tions were made at Montsouris, 3 kilometers south of the observatory 

 of Paris. The conditions at each place are nearly the same. In fig. 

 8 the rainfall is represented by vertical lines, the height of which corre- 

 sponds to the quantity of water which fell at Paris from 1689 to 1896, 

 except during the three intervals already mentioned. The diagram 

 is interesting, not only as an exact record, but because it indicates the 

 gradual increase in the rainfall of Paris for the last 200 years. This 

 increase can be seen in the accompanying table, where the averages 

 are given for certain periods : 



Annual rainfall at Paris since the year 1689. 



Tear. 



1689 to 1719 

 172(1 to 1754 

 1773 to 1797 

 1804 to 1824 



Rainfall. 



Mm. 

 485.7 

 409.4 

 492.5 

 503.7 



Tear. 



1825 to 1844 

 1845 to 1872 

 1873 to 1896 



Rainfall. 



Mm. 

 507.5 

 522.4 

 557.4 



It appears that the rainfall in Paris has increased from period to 

 period, or that the older observations were not carefully made at the 

 observatory at Paris. 



The condition of the sky during the 24 hours of each day for the 

 year 1896 was noted as follows : 



Condition of the sky during the year 1896. 



It is seen that the cloudiness was very great during the year. The 

 sky was beautiful in May but almost entirely overcast during January 

 and December. There was on an average one rainy day to two days 

 without it, and during 202 days the sky was completely overcast or very 

 cloudy. 



SUBTERRANEAN WATERS. 



The thickness of the water sheets of wells and the temperature of 

 these waters have important climatological bearing. Observations were 

 continued on two wells, the first 13.56 meters and the second 14.08 meters 

 deep. The temperature of the water in each well was as follows : 

 6216— No. 3 2 



