80 Dr Heineken's Meteorological Journal kept at Funchal. 



in the open air ;"" but here the result would be, and actually is, 

 diametrically opposite. Should health and other concomitants 

 permit, I shall endeavour next year to obtain maxima from se- 

 veral instruments, and in the meantime, should feel obliged 

 by any hint as to the readiest and most correct mode of making 

 maxima observations on temperature in such a latitude as 

 this. C. He I NEK EN, M. D. 



Funchal, Madeira^ ^5ih October 1825. 



Q3SERVATI0NS BY THE EDITOR. 



The very judicious and candid method which Dr Heineken 

 has taken to remove the doubts which we expressed in a for- 

 mer Number, (No. xvii. p. 171,) respecting the accuracy of 

 his measure of the mean temperature of Funchal, has satisfied 

 us of the correctness both of his instruments and his observa- 

 tions. We committed a mistake in asserting that Humboldt 

 made the mean temperature 72°. 22, for it is only 68°.5 in his 

 Treatise on Isothermal Lines ; but it was still a matter of sur- 

 prise to us, that the mean temperature should be so low as 

 64!°.3, when Humboldt gave 64°.04 for the mean temperature 

 of the coldest month. It will be generally found that the mean 

 temperatures of all warm climates are given too high, not only 

 from the difficulty of protecting the external thermometer from 

 the indirect influence of the sun, but also from the want of a 

 sufficient number of evening and morning observations. Hence 

 we are disposed to think that the temperature of 68°.5, as given 

 by Humboldt, would require to be diminished from both these 

 causes. 



The following are the different measures which have been 

 given of the mean temperature of Funchal. 



