368 Analysis of Scientific Books and Memoirs. 



rizontal direction of the motion ; the perpendicular shocks, by a force 

 acting from below upwards, which supposes a much greater depth in the 

 situation of the acting force, than the other, without ever being in any case 

 nearer the surface. Every one may easily distinguish the difference which 

 subsists between the superficial motion caused by the rapid passing of a 

 heavy carriage, or by the sudden combustion of a large quantity of con- 

 fined powder, which would cause the darting of a large accumulation of 

 electric fluid to restore the equilibrium between the earth and the atmos- 

 phere, were it possible for it to collect in the midst of so many conducting 

 bodies which seem designed to restore the equilibrium instantly ; between 

 this motion and the deep, heavy" earthquake, armed with such terrible 

 power, which agitates so violently a great extent of the globe, which 

 sometimes seems ready to tear it from its very foundation, and which has 

 all the characters of an effect sprung from most wonderful degrees of 

 force, and of force which, placed deep in the earth, moves and convulses 

 those great masses lying between it and the surface. 



The idea of forces and effects like these, fills with fear the miserable 

 mortal who creeps upon the face of the earth, and brings his pride down 

 to the dust. When he sees the earth reel, and the great fabrics which he 

 has raised with so much confidence rushing to ruin, he despairs of find- 

 ing any where one firm support to his frail existence. 



The chinks and fissures formed in many places, and to which the vul- 

 gar attribute much importance, are in consequence of the quaking of the 

 soil, and to which the softness of the earth, and the loss of its internal 

 support have given rise. The country of Bosco. about Ogliastro, of which 

 I have already spoken, became furrowed with diverse, long, tortuous, 

 deep clefts, the sides of which, in some places, sunk down ; in other 

 places, portions of the surface passed down over inclined planes below 

 them, and took new positions ; the olive-trees which some of these carried 

 with them, were much injured by the breaking and displacing of their 

 roots. This land is formed of an immense deposit of argillaceous chalk, 

 more than a hundred feet deep. The water which penetrated it (and the 

 winter there was very rainy) loosened the earth, and carried a great 

 part of it into the internal cavities below ; the surface, thus wanting solid 

 support, under the shock of the earthquake, became filled with depressions, 

 caverns, and inequalities. The same may be said of a great aperture made 

 in the vicinity of Colesano, which, dilating itself day after day, threatened 

 to render those places inaccessible. Copious showers alone produce such 

 effects in the chalky land of many parts of Sicily. This want of firm 

 bases frequently causes the overthrow of great rocks at the time of earth- 

 quakes. Well do we remember, that, in the earthquake of the 5th of 

 February 1783, a mountain, a mile to the south of Scilla, and which was 

 a mile and a half in length, fell over into the sea of Calabria, and formed 

 two new promontories. 



If all these facts induce us to place in Eolia, the causes of the physical 

 events of the past March, it is necessary to inquire if these islands exhi- 

 bited, at that time, any phenomena, which may corroborate our opinion. 



