FOR HKJH LEVELS IN THE EARTH S ATMOSPHERE. 



67 



2.0^7 2.4^ Z'fS> 



Fig. 4. Chart of n"""" forSa. m., September 23, 1898, or lines 



Fig. 5. Cliart of n^^ °°° for 8 a. m., September 23, 1858, 



of equal differences of barometric pressure between sea level and the 40000 of equal differences of barometric pressure between the 40 000 and 

 potential surface of gravity as telegraphed from all stations to the Central potential surfaces of gravity as telegraphed to the Central Office. 

 Office. 



r lines 

 SO 000 



29.6' 



29.9 



Fig. 6. Chart of m or isobars for sea level for 1898, September Fig. 7. Chart of p^o ooo for 1^98, September 23, 8 a. m., or iso- 



23, 8 a. m., as observed and telegraphed. bars at the 40 000 level surface as deduced from the isobars for sea level 



by subtracting the numbers on Fig. 4 from those on Fig. 6. 



