AT MADEIRA. 



70 



the heating effect of the forenoon sun on the too thin Venetian blinds of the open window 

 within which said thermometer was suspended. 



Lastly, the Thermometer observations of the French bulletins from Funchal have been 

 first reduced from Centigrade to Fahrenheit ; and then, having been taken at 7 h. A.M. each 

 day, have had a co'rrection of -f- - 8 F. applied to them to reduce them to the mean of the 

 24 hours ; that quantity being th of the mean daily range of temperature in Madeira for the 

 period of observation. 



When monthly means are to be found from the above daily observations, which do not, 

 in case of either of the two months included, cover their whole extent, a correction is 

 required wherever the meteorological quantity concerned is largely and regularly progressive 

 with the time. Probably this is only practically necessary with the mean temperature ; but 

 for its average rate of progression through the months May, June, July, and August, viz. of 

 2.5 for 30 days, our observations in June deficient by the first 7 days need a correction of 

 0.6 F. ; and those of July, deficient by the last 6 days, a correction of +0.5 F. These 

 corrections have accordingly been applied to the mean temperatures entered above. 



