134 



Prof. J. Prestwich. 



eruption of December, was witnessed by M. Menard de la Groye,* who 

 remarks that "towards the end of May the well-waters of Torre del 

 Greco and Torre dell'Annunziata failed, and that this was an ordinary 

 precursory symptom of the eruptions." In June the waters continued 

 further to lower, and " in the first fortnight in July they fell so low 

 as to alarm the population," while "in October the wells of Resina, 

 Torre del Greco, and other places failed in a surprising manner." 



Professor Phillips briefly recordsf the following instances : — " July, 

 1804. Severe earthquake — diminution of springs." In May, 1812, 

 the wells failed or were much lowered at Torre del Greco and Resina, 

 as well as a thermal spring. In June, July, and August, heavy rains 

 occurred ; yet this did not restore the water in the wells, which still 

 remained low, and even lower than before in September, and this 

 scarcity was felt along the whole Vesuvian coast, and in the valley of 

 the Sarno. Early in 1822 the wells lost their water. August, 1833, 

 water failed in the wells.]: The loss of water has sometimes been 

 attributed to other causes, such as the state of the rainfall, &c, but 

 Professor Phillips specially observes that this sinking of the wells 

 cannot be explained by reference to the previous state of the 

 weather ;§ and, after a careful examination into all the phenomena 

 connected with the eruptions of Vesuvius, he alludes again to " the 

 sinking of water in the wells around Vesuvius — the total drying up of 

 some, and the increased descent of the bucket in all," during times of 

 volcanic disturbances, as an important fact. 



M. Ch. St. Claire Deville|| remarks : " It is well known that there is 

 only one tolerably certain indication of an approaching eruption of 

 Vesuvius, and that is the disappearance of the water in the wells of 

 Resina and Torre del Greco." 



According to Poulett-Scrope,^[ the threatening indications of an 

 approaching crisis " are accompanied by the disturbance or total dis- 

 appearance of springs, and such accidents as the cracking, splitting and 

 heaving of the substructure of the mountain must naturally occasion." 



Professor Guiscardi, of Naples, in answer to my inquiry, writes,** 

 " As a rule, the water of wells in the neighbourhood of Vesuvius 

 undergo changes in quantity, and even quite disappear before the com- 

 mencement of eruptions. Only as well as I know in the eruption of 

 1861, the phenomena followed the eruption. I add a list of such 

 diminishing and drying wells. 



* " Journ. de Phys. et de Claim.," vol. lxxx, p. 390. 



t " Vesuvius," p. 96 et seq. 



% Ibid., p. 140. 



§ Ibid., p. 141. 



|| " Bull. Soc. Geol. de France," 2nd Ser., vol. xiv, p. 254 (1856). 



1 " Yolcanos," 2nd Edit., 1862, p. 21. 



** Letter to the author dated 1st Sept., 1881. 



