[6] (P. 134). That the causes assigned by Professor Palmieri for the potent developments of electricity (positive or negative) which characterise the ascent of the issuing columns of (chiefly if not always) _dry_ steam, with a relatively small volume of various gases, and throwing up, in their blast, volumes of small solid particles in ashes and lapilli, etc., and the subsequent fall as a mineral or stony hail-shower of the latter, through the partially condensing vapours and the circumambient air, are the main causes of electrical development evidencing itself in lightning flashes, is no doubt true. We must not, however, lose sight of the many other and very effective agencies at work here to produce electric excitement. The actual _bocca_ of the volcanic vent whence the steam roars off constitute the cone a veritable hydro-electric machine. Mechanical energy in various forms is transformed into electric energy. Chemical action is going on both in the solid and in the vapourous and gaseous emanations as they rush into and remain in the air or descend from it, and chemical action is transformed in part into electric energy. Percussion between ascending and descending particles and fragments, fractures and breaking up of more or less of these, thus and by sudden changes of temperature in cooling, are likewise operative. In addition, great and violent movements in the atmosphere itself result from the large local accessions of temperature by the heated volume driven up into it, and which in turn give rise to electric disturbance of the same character as those produced in wind storms and whirlwinds, brought about by the natural causes which every day effect disturbances in our atmosphere all over the globe. [7] (P. 135). The views stated in note 3 (to page 96) may here again be referred to as in point. How is it possible, in the present state of science at least, to establish any physical connection between an eruption in Java and one of Vesuvius, "with half the world between," when not even having the solitary connecting link of complete contemporaneity, and which, if it existed, yet might be nothing but accidental? A list of shocks upon record, which have occurred more or less nearly simultaneously at distant parts of the world, may be found in my fourth Report, ("Facts of Earthquakes," "British Association Reports, 1858") and the reasons are there given for rejecting the notion of any direct physical connection between the origins of the respective shocks. Shocks, emanating from the close neighbourhood of volcanic vents, or simultaneity of eruption, in vents not far distant from each other, stand upon a different footing. Transcriber's Notes. Preserved the unusual, but consistent, spelling of "develope."