178 



Mr: Nixon on the Theoti/ of the 



fSEPT, 



Table IV. — Correction for the diminished Specific Gravity of 



the Air, 



Altitude iibove the Sear. 



Altitude above the Ste. 



feet. 



Rule. — Enter the Table with the altitudes above the sea of 

 the upper and lower stations, and add the difference of the 

 corresponding corrections to the altitude, or difference of level. 



