458 PHILOSOPHICAL TRANSACTIONS. [anNO 1740. 



was seen to rise gently, to 2° ot' rectangular elevation, and to 20° of horizontal 

 amplitude. This phenomenon was seen all over Italy, as appears by several ac- 

 counts of it, though with some disagreement between them. 



The most probable opinion as to the cause of this phenomenon, ascribes it 

 to the simple firing of a bituminous and sulphureous matter, on account of its 

 very little specific gravity, raised to the upper parts of the atmosphere, and 

 there, by the clashing of contrary winds, broken, comminuted, and at last set 

 on fire. This opinion has been defended with strong arguments in the Peters- 

 burg commentaries, by Mayer, on occasion of the appearance of a similar 

 phenomenon in those northern countries. And indeed the preceding eruption 

 of Vesuvius, the contrariety of the moving forces, the readiness of the matter 

 to take fire, the unequal intenseness of the light, the streaks, and all the other 

 circumstances observed in this meteor, are plain arguments of a genuine and 

 real accension. And Wolfius, on the appearance of a phenomenon much like 

 this, which was seen all over Germany on the 17th of March 17 17, is of opi- 

 nion, that it should be called imperfect lightning, as being produced by the in- 

 flammable matter of lightning. 



2. Observed at Padua, by the Marquis Poleni, F. R. S. p. 587- — At the 

 time of this meteor, the air was calm, and the barometer was remarkably 

 high. 



At 5\^, there appeared near the horizon a blackish zone, with its upper limb 

 of a sky-colour, somewhat obscure. Above this zone was another very lumi- 

 nous, resembling the dawn pretty far advanced. The highest zone was of a 

 red fiery colour. The altitudes of the zones seemed to bear such proportion, 

 that the second was double the first, and the third triple; and in many places 

 they rose somewhat above the 40th degree of altitude. Eastward they extended 

 to the 55th degree on the horizon, and westward to the 70th. 



It is remarkable, that after sun-set on the preceding days, as well as this, 

 there appeared in the west a remarkable redness expanded on each side; and 

 on the ensuing evening, the same bright red colour, appearing near the hori- 

 zon, deceived the common people into a belief, that a new phenomenon, like 

 the foregoing, was breaking out of the horizon. Near our zenith there ap- 

 peared some thin lucid clouds, partly of a whitish red, in such a manner, that 

 they seemed as if occasioned by the burning of houses at some distance to 

 the north. Others of this sort had happened before, and some were seen 

 afterwards. 



A little after 6, the upper parts began to emit red streamings, or rays, in 

 plenty ; but in these the red was now and then intermixed with whitish and 

 darkish colours. In a few seconds after, there issued out from the very equi- 



