118 Dr Brewster on the Mean Temperature of the Equator. 



element in meteorological investigations, I have examined the 

 evidence in favour of this new result, and I have no hesitation 

 in expressing the conviction, that the result given by Hum- 

 boldt is founded on just views of the observations which he 

 possessed ; — that it is a near approximation to the truth, — and 

 that the temperature of the equator cannot be placed higher 

 than between 81° and 83° of Fahrenheit. 



When Humboldt, in his admirable paper on Isothermal 

 Lines, fixed the mean temperature of the equator at 81 J°, he 

 naturally gave a preference to observations made in the old 

 world, where the distribution of temperature did not exhibit 

 the same anomalies which occur in the New World. He ac- 

 cordingly used the mean temperatures of Senegambia, Madras, 

 Batavia, and Manilla,* whereas Mr Atkinson, neglecting en- 

 tirely the temperatures of the Old World, deduces his results 

 solely from the American observations. Mr Atkinson is there- 

 fore not correct in stating, " that it appears, from data fur- 

 nished by himself, that Humboldt has fallen into an error 

 when he asserted that the mean temperature of the equator 

 cannot be fixed beyond 81 J ." 



Having sometime ago received, through the kindness of 

 Henry Harvey, Esq. a series of excellent meteorological obser- 

 vations made in Ceylon, I felt myself in a situation to throw 

 some light on this important point ; and in order to obtain 

 still more general, results, I wrote to Professor Moll of Utrecht, 

 for the purpose of obtaining some of the recent observations 

 made in Java. The following are the Ceylon observations. 



Mean Temp. 

 Trincomalee, - - 80°.56 



Point de Galle, - - 81 .1 



Colombo, - - - 80 .75 



Kandy, f - 78 .5 



Do. according to Dr Davy, - 79 .2 



If we now deduce the equatorial temperature from these 



T 



* By the formula Eq. Temp.= T where T is the mean tempera- 

 ture of any latitude L, the mean temperature of the equator, deduced from 

 these four places, is exactly 81° .5. 



t A correction of 5°.7 is added for altitude, according to Mr Atkinson's 

 formula. 



