VOL. XLVII.] VHILOSOPHICAL TRANSACTIONS. 231 



by the loose soil, and steepness of the road. About 8 o'clock, in the morning 

 they gained the summit or caldera. It is about 12 or 15 feet deep: the sides, 

 sloping down to the bottom, form a concavity, or crater, resembling a truncated 

 cone, with its base uppermost. The crater seems nearly circular; its diameter 

 about 40 fathom. The ground is very hot; and from near 20 spiracula, as from 

 so many chinmeys, \ou perceive a smoke or vapour of a strong sulphureous 

 smell. The whole soil seems mixed or powdered with brimstone, which forms a 

 beautiful coloured surface. 



One of the rocks forms a sort of vault or nich ; against which the vapour con 

 densing produces what the inhabitants call azufre de gota, or drop brimstone. 

 The nich, against which the vapour is condensed, is of a greenish colour, spark 

 ling with yellow like gold. The same colour you perceive on almost all the 

 stones thereabout. A small part of the Sugar-loaf is white like lime ; and there 

 is another less part, whose internal substance seems a sort of red clay, and whose 

 superticies is covered with a salt. 



In the middle of one of the rocks was a hole, about 2 fingers breadth in dia- 

 meter, whence proceeded a noise like a great body of liquor boiling very strongly; 

 and one of the company burnt his hand by applying it to the spiraculum at 4 of 

 a yard distance. This Sugar-loaf is covered with snow the greatest part of the 

 year. The snow was lying on it from October 1742 to June 1743. 



The different accounts of various authors concerning the height of this famous 

 peak would have induced one less inquisitive than Mr. H. to satisfy his curiosity, 

 by examining its real altitude : for which end, between 3 and 4 o'clock in the 

 afternoon of a very serene day, when not a cloud appeared, either on the sum- 

 mit, or in the whole atmosphere, (to prevent any accidental refraction) having 

 pitched on a plain along the sea-side for a horizontal stand, and measuring tri- 

 gonometrically a base sufficiently corresponding to the angles with the greatest 

 accuracy, he observed the height to be 2566 fathoms, or 3 miles, wanting 

 only 74 fathoms. Two subsequent observations by himself, as well as 2 ante- 

 cedent ones some years before by John Crosse, Esq. the British consul, served 

 only to confirm his opinion of the justness of this observation. 



Though the body of the mountain is covered with clouds, the peak is gene- 

 rally seen above them quite clear ; but sometimes the contrary happens ; the 

 whole body of the mountain without a cloud, and only the summit of the peak 

 covered with a thick white cloud, as with a cap. This is often observed in the 

 finest weather ; when the Spaniards say, El Pico tiene su sombrerillo puesto ; i. e. 

 • The Peak has put his little hat on ;' and think it a certain sign of rain. 



During 6 or 7 years, that Dr. H. lived in the villa of Oratava, as he had a 

 continual sight of the peak, he several times observed the above phenomenon, 

 and did not remember one instance in which the prediction of rain failed. 



