VOL. XXXVII.] PHILOSOPHICAL TRANSACTIONS. 555 



An extraordinary Eruption of Mount Fesuvius in March 1730, extracted from 

 the Meteorological Diary of that Year at Naples. Commitnicated by Nichol. 

 Cyrillus, M. D. R. S. S. N° 424, p. 336. 



The thermometer used in this Diary, was made by Mr. Hauksbee, in which 

 the freezing point is marked at 65° under the point extreme hot ; but the doctor 

 observes, that at Naples water will freeze when this thermometer stands at 55° 

 only: which, according to him, seems to argue, that there is something else 

 besides an intense degree of cold required for freezing water; that the air of 

 Naples abounds in it, more than the air of London ; and that this may proba- 

 bly be of a saline nature ; because when we turn water into ice by the help of 

 snow, it is necessary to mix salt with it. 



March, Therm. Whids. " 



8, 40 O s. 3 Cloudy weather; strong south wind. Vesuvius 

 sent forth a great smoke and stream of fire, with hollow 

 rumbling. 

 Q, 38 O w. 1 The weather cloudy. The following night Vesu- 

 vius thundered as it were twice. In the day the windows 

 trembled a little. 

 10, 11, ? 5 Cloudy; rain now and then : 



12, i^^ ° ^' ^ i. The clouds hide the smoke and fire. 

 13 41 1 N.w. ] Weather rather clear. The smoke lessened. 



14, 47 O N. 2 A little rain in the night; in the morning snow 



in the mountains. In the forenoon the snow increased 

 again. In the evening after 8 o'clock the fire arose to 

 a vast height, and threw huge stones to almost half the 

 perpendicular height of the mountain. Pumice stones red 

 hot of 1 or more oz. weight, were driven several miles 

 like a shower of hail, and frightened away the birds. 

 In about an hour's time the height of the flame was some- 

 what lessened; and through the middle of the thick smoke 

 flashes of lightning were often seen. 



15, 50 N. E. 1 Clear weather. Thick\ smoke scattered the ashes 



many miles over the sea. 



16, 48 s. 1 Clear in the morning; about noon cloudy, small 



rain and cold. By change of the winds the smoke and 

 ashes were carried towards the N. Clouds hide the 

 mountain. 



17, 40 1 s. 1 A few thin clouds. The sinoke turned with the wind. 



4 B 2 



