V. 



TABLES 



FOR REDUCING BAROMETKICAL OBSERVATIONS TO ANOTHER LEVEL, AND FOR COMPUTING 

 DIFFERENCES OF ELEVATION MEASURED BY THE BAROMETER, BY M. C. DIPPE. 



In No. 1088 of the Astronomische Nachrichten, published in June, 1857, Dr. 

 DiPPE gives the following set of Tables for reducing barometrical observations to 

 another level, and for computing heights. These tables, being based, as the preced- 

 ing ones (IV.), on the formula of Laplace, and computed with the same constants, 

 give results nearly identical, but dispense with the use of logarithms. 



Use of the Tables. 



The tables suppose the height of the barometer to be expressed in French inches 

 or Paris lines, and the temperature in degrees of Reaumur ; they give the differ- 

 ences of level in French toises. 



The signs used have the following signification : — 



At Lower 

 Station. 



At Upper 

 Station. 



B = Observed Height of Barometer in Paris lines. 

 T = Attached Thermometer in degrees of Reaumur. 

 b =^ Barometer reduced to the freezing point. 

 t = Temperature of the air, detached Thermometer. 



B' = Observed Height of Barometer. 



T' =: Attached Thermometer, 

 j 5' = Barometer at the freezing point. 

 I t' = Temperature of the air. 



(j) = Latitude of the place. 



h = Difference of elevation between the two stations. 



I. For Reducing Barometrical Observations to another Level. 



Given, h in toises, t, t', ^, and b or b'. 

 To find b or b'. 



Make first 2 r = — "t- and t, and 

 D 60 



