Dr Heineken's Meteorological Journal kept at Funchal 79 



out the day. As, therefore, there appeared to be but two re- 

 sources against this inconvenience, viz. several instruments in 

 different situations and noted at different times, or a register 

 thermometer within doors, and having a room over it, I chose 

 the latter, and in the Philosophical Magazine for November 

 and December 1827 gave the results. These have been in a 

 very fair and candid manner objected to in this Journal, (Ed, 

 Jour, of Science, No. xvii. p. 171,) and I am glad of the op- 

 portunity which it affords of repeating why I deviated from the 

 usual mode of taking the maximum observations, and of my 

 doubt whether any taken out of doors with a single and sta- 

 tionary instrument can be strictly correct for shade maxima, 

 in a latitude where the sun is so vertical. Upon this the whole 

 question appears to me to hinge. If observations made in as 

 perfect, or rather imperfect, shade as a stationary instrument 

 can insure, be admitted as correct, then the mode which I 

 adopted is certainly a bad one, and its deductions false; but if 

 such as are made upon several instruments are alone to be 

 trusted to, it is I think the lesser of two evils; and, was there 

 not the weight of such authority against me, I should almost 

 be bold enough to prefer the mean which thence resulted to 

 that obtained by the other mode. Dr Brewster''s Formula I 

 own staggers me more than the other authorities, because they 

 were not from observations made upon the spot for any length 

 of time. In the quotation of Humboldt's there must, I think, 

 be some mistake. It is stated to be 7^.22 ; but in the transla- 

 tion (I have not the original) of his " Personal Narrative,^'' it 

 is given by him, on the authority of Cavendish, 68.9 ; and 

 Santa Cruz, on the south side of Teneriffe, four or five degrees 

 more south than Funchal, and wo^oriow^Z// hotter, he gives o/i/y 

 71.10.* Kirwan makes the mean of Funchal 68.9, — and I 

 in 1824 made it 68.2, and in 1825, 68.6,— by an out-of-door 

 stationary instrument. It appears then, I think, satisfactorily, 

 that the dissonance of result is entirely to be attributed to the 

 different mode of making the observations, and not " to some 

 error either in the instruments or in the observations." In a 

 higher latitude an instrument within doors would, as it is ob- 

 served, " give a higher temperature than if it had been placed 



M. Von Buch is quoted in tbesame PijbUciUkMi as making it ?U. 



