On the mean Temperature of Funchal, fyc. 171 



from 1807 to 1827 inclusive; but as these were made only at 8 h a. m. and 

 2 h p. m. they want an evening observation, and give ordinates of the daily 

 curve, from which it would have been impossible to deduce the mean tem- 

 perature, had we not been enabled to supply the defect from the hourly 

 observations made at Leith. Thus the mean temperature at Penzance at 

 8 h a. m. and 2 h p. m. is — 54°5. But by the hourly observations at Leith 

 for 1824, 1825, and 1826, the mean of 8 h a. m. and 2 h p. m. exceeds the 

 mean temperature of the twenty-four hours by 2°.03. Hence we obtain — 

 Mean tem. of Penzance for 21 years, at 8 h a. m. and 2 h p. m. 54°.5 

 Correction, ------ 2.03 



Mean temp, for 21 years corrected, - - - 52°.47 



A result which differs very little from the mean of the maximum and mi- 

 nimum register thermometer. 



The mean of all the observations together is 52°.23, agreeing in the most 

 extraordinary manner with the result of Dr Brewster's formula. 



5. Dr Heineken on the Mean Temperature of Funchal, &$c. An ela- 

 borate Meteorological Register of the weather for 1826, kept by Dr Hei- 

 neken at Funchal in 1820, has been published in the Philosophical Magazine 

 for November and December 1827. 



The observations for the temperature were made 89 feet above the 

 sea, with a maximum thermometer by Newman, and minimum one 

 by Dollond ; and the mean deduced from them is 6»4°.3, — a result so 

 low, that we are persuaded there is some error either in the instruments 

 or in the observations. The annual mean temperature of Funchal, as 

 given by Humboldt, is 72°.22, and the mean temperature of the coldest 

 month is 64°.04, fully as high as the annual temperature given by Dr 

 Heineken. Dr Brewster's General Formula gives the Mean Temperature 

 of Funchal 68°.65, equal nearly to the mean of Humboldt's and Heineken's 

 results, which is 68°26. Dr Heineken's maximum thermometer was 

 hung in a room with the door and window always open, which ought 

 to have given a higher temperature than if jit had been placed in the 

 open air. 



6. Water-spouts in the Indian Ocean. — According to Mr Main, the wa- 

 ter-spouts in the Straits of Malacca and Singapore arise from the con- 

 vergency of the air and the clouds to the spaces left unoccupied by the 

 heavy and impetuous rains which precede them. " These generated vari- 

 ous and contrary currents of air, wheeling the clouds in violent commotion ; 

 partial tornadoes were consequently created ; these, by their vertiginous 

 course, affected the adjacent and surrounding vapours, drawing them into 



Kthe vortices. The grosser parts of this whirling body of vapour naturally 

 inclined to the centre of the tornado, and these coalescing, formed the 

 aqueous column called a water-spout. 



" The first appearance of this phenomenon is the lower end of the co- 

 lumn impending from the base of a dark cloud, in the shape of an inverted 

 coije, in a somewhat waved direction, descending gradually to the sea or 



