XVIII 



ON THE REPRESENTATION OF THE DISTRIBUTION OF 

 ATMOSPHERIC PRESSURE BY SURFACES OF EQUAL 

 PRESSURE AND BY ISOBARS 



BY PROF. DR. WM. VON BEZOLD 



[Archives N 6erlandaiscs dcs Sciences exactes et naturelles, Series II, Tome VI, 



PP- 5^3~574< 1 90i. Translated from Gesammelte Abhandlungen von 



W. v. Bezold, Berlin, igo6, pp. 306-jij] 



In order to obtain a clear idea of the distribution of pressure in 

 the atmosphere we imagine surfaces of equal pressure extending 

 through the atmosphere for a series of pressures differing from each 

 other successively by a given constant difference. As such con- 

 stant we most frequently adopt 5 millimeters, that is to say, we 

 consider surfaces for which the pressures are given in millimeters by 

 the equation 



P = 760 ± 5 n 



so that the constant difference is A /? = 5. In special cases we may 

 also choose J/?=2-5orJ/?= i.o mm . 



If now we seek the "traces" or intersections of these surfaces with 

 any other surface of known location and form, then we obtain lines 

 of equal pressure or isobars in the most general sense of this term. 



As such surfaces of known location and form we choose either 

 "level surfaces of gravity" in which case the traces are isobars in 

 the ordinary sense, or we seek the intersections with a vertical 

 surface in which case we speak, but not quite correctly, of the repre- 

 sentation by means of "baric surfaces." 



Both these methods of presentation have their special advantages 

 and disadvantages which I will elucidate more clearly in the follow- 

 ing lines. 



If it be not possible to avoid restating many well-known points, 

 still I imagine such reconsideration by no means superfluous, since 

 it would appear that many of those who daily make use of either 

 of the two methods of presentation, in spite of the publications of 



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