444 Second Appendix. laid open, but prifms were never found among them, nor weie any found in the caverns of Monte Roffo, nor in the fubterraneous galleries ofthofe currents. Ponces, 446, 447. Gioeni, in bis Latalogue of the Minerals of Vefuvius, intirelv omits them; and teils us, “ The bafalts are cer- “ tainly of voicanic origin, yet volcanos in our “ days feem to have loft the povver of producing « them.” Introduktion, LI1I. Perhaps I may be told that Sir William Hamil ton obferved fome bafaltic pillars near Torre del Grsco; but Sir William’s own words are, “The ** lava of Vefuvius that runs into the fea near 4 * Torre del Grieco, has an^evident tendency to the bafaltic form ; on Mount Vefuvius I never “ faw any thing like bafalts except that at Torre * e de! Grsco and fome fragments throvvn up by “ the eruptioH of 1779 * ” Of the latter we ihali prefently lpeak, but the former werc not bafalts, as it feems; for, Gioeni teils us, “ I wilhed to verify the bafalts which I was told were to be “ found on the fea-coaft near the park of Portier, “ butl difcovered nothing but a courfe of com- ** pakt lava with very irregulär perpendicular €C fiffures, whence refulted quadrangular and tra- pszoidal columns. Such fiffures are often ob- ** ferved in tufas, and earths of different kinds, “ and can impofe on no onc, habituated to dif- “ tinguilh their true caufe. The only bafalts I *' found on Vefuvius were thofe erupted in 1779, “ which were collcöed by Sir William Hamil- “ ton.’’ It is even doubtful whether what he calls compact lava be really fuch, as moft of the voicanic obtervers liave hithcrco confounded the * riill. Tranf. 1786, p. 376. mother-