1887.] Its Reduction to Sea Level, 265 



In conclusion I will give two cases, to show how erroneous it is to 

 take temperature into consideration on elevated table lands. Assume 

 two stations ten miles apart, situated on a plain, both having the same 

 altitude and barometer reading, while the temperature of one is 10^ 

 warmer than the other. Upon a chart plotted on the plane of these 

 stations both pressures would be alike, which is the truth, but upon 

 their being reduced to sea level they are totally different, which is an 

 untruth, but by my mode of reduction the truth would exist, even at 

 -the sea level. 



The other case is this. Often when pressure has been very steady 

 all over the Colony, the diurnal range of temperature at an elevated 

 station has been very great. Now if the readings had to be reduced 

 to a steady sea level pressure the upper barometer must have oscillated 

 very much, but as such was not the case, the effect of temperature 

 must have been 7iil. Major Pinto, a traveller who crossed Africa from 

 Benguela to Natal, notices this. He says : " Whoever bestows any 

 attention upon the meteorological observations I publish, will see that 

 the atmospherical changes in this part of Africa have but a slight, if 

 any, influence upon the pressure, which remains the same amid the 

 most sudden variations." 



And again he says : " An investigation of these tables will shew 

 the great uniformity of the barometrical oscillations and the enormous 

 inequalities of temperature and humidity of the air in the countries to 

 which they refer." The country Major Pinto refers to is the great 

 ftable land of Central Africa, far from all influences of atmosphere 

 Jjeloiu the places of observation. 



ADOLPH G. HOWARD 



Cape Town, 28th September, 1887. 



