418 



F. Dellmann on Atmospheric Electricity. 



observations can be made, or if made, it must be with great 

 caution. Our observatory is, it is true, surrounded by some 

 houses, but it is situated outside the town. 



An increase in the atmospheric electricity proportional to the 

 height could not be detected at Kreutznach ; its increase was less 

 than such proportionality would demand, but its law could not 

 be discovered. 



At Kreutznach the extremes of the observed quantities lie 

 further asunder than in the Brussels observations. This is 

 partly due to the fact that our observations ai'e more frequently 

 made, but partly, too, because the aiTaugement of the measuring 

 instrument at Kreutznach permits of a more accurate determina- 

 tion of these extremes. Very small quantities can be measured 

 with the same accuracy as large ones, since, when the method of 

 the angle of deflection does not suffice for the measurement of 

 these extremes, that by torsion is applied. 



The following numbers show the daily variation of the atmo- 

 spheric electricity. In February, when observations were gene- 

 rally made every two hours from 6 a.m. to 10 p.m., these numbers 

 were 

 113-5, 139-1, 163- i, 158-5, 151-0, 173-8, 179-4, 167-3, 156-7. 



On the 18th of March, when an observation at 7 p.m. was 

 added, the numbers were 



102-6, 167-5, 173-3, 212-2, 178-1, 159-0, 118-8, 173-3, 

 179-3, 102-6. 

 Observations every four hours on the 2nd of June gave 



221-0, 131-5, 102-6, 70-1, 120-8. 

 The numbers on the 9th of July, determined every four hours 

 as well as at 8 p.m., were 



183-8, 121-8, 106-0, 1140, 141-7, 121-3. 

 A few examples are added to show how quickly the tension in- 

 creased after sunrise. 



October 4. 



