OCR Text |
Show 244 ITS FIRST APPEARANCE. were heard. Shocks of earthquakes had, indeed, been felt hy ships passing the same spot on the 28~h of June· but there was then no appearance at ~he surface ~f the sea. At about eleven o'clockS<?nT e lOth Captain Carrao, who commanded a 1c1 1an brig,' and was then about twenty ~iles off Cape St. Mark observed the water' at the dis~ance of a gunshot 'in a state of agitation. A portwn, more t?an a hu~dred fathoms in diameter, rose up to the height of sixty feet ; and discharged volumes o~ sulphur<?us smoke The elevated mass, as there IS no ac.twn f th . atmosphere mentioned that could sustain a ~olu~n of water to that height, must have been steam That steam, however, from the supply of a whole. sea of cold water, and the powerful actiOn of the fire under it, may have bad the colour and apparent density of a mass of water. Indeed, the external part of it must hav~ been condensed, and descending in a thick fog, wh1Ch fog would be kept from spreading on the surface of ~he se~, b~ the wind which must have set towards 1t mall dtr~ctwns, to supply the air which was constantly ~arefymg and ascending over it. The smoke mentwned by the Sicilian captain was, mos~ probably, the hottest art of the steam, because 1f the beated strata had ~0 broken under water as to allow volumes of. real smoke to escape, the solid matters would not hkely have reached the surface. It appears fr<?m the _observations made by other vessels, that the 1mm?dmte bottom was mud, and that the depth, . after the tsland was formed was one hundred and thuty fathoms, at the distanc~ of one mile. That was nearly three hundred and thirty-eight pounds (say three hundred wei ht) on the inch, from the mere pressure of the wat~r, without taking into the account th~ condensation, the weight of the mud, and the res1star:c~ of the strata which there are no means of ascerta~mng; but they,' in all probability, exceeded the s1mple pressure of the water. FORCE OF ITS ASCENT. Now, if we suppose that the surface, acted under by the heat, was only a circle of about one hundred and twenty fathoms in diameter, we shall form a rude estimate of the power employed. The surface is about 11,310 square fathoms, or 407,160 square feet, or 56,631,040 square inches, which at three hundred weight on the square inch, gives a pressure from the weight of the water alone of the vast amount of 8,794,656 tuns. But as there were other and probably greater, resistances to overcome, th~ force exerted at that single spot must have been far greater than would suffice to blow all the navies in the world into the air. That spot, too, was but a mere point on the surface of the globe ; so that it is utterly impossible to imagine any material weight or material strength, which those powers could not overcome. It is only under the pressure of a depth of water that such a phenomenon could take place, as the water both supports and consolidates the upper part, and so enables the crust to rise in a mass, which in the air, would burst and discharge the melted matt'ers in an eruption, as is the case in those volcanoes that are on land. The second observation of Hotham Island was made on the 13th, two days after the first; and the account was,-the appearance of columns of smoke the hearing of a sound like that of the paddle-wheP-1~ of a steamboat; and dark matter rising up to a height, and then falling with force into the sea: all those appearances, which we have stated in near!} the words of the eyewitnesses, agree in establishing the same fact; namely, that by that time the volcanic matter had reached the surface, and been broken when it came in contact with the air, or even when so near. t~e. surface that the pressure upon it was much dtmm1shed. The smoke was a sure sign that the surface was reached, the hissin<T was the solid matter coming in contact with w:ter at a lower X2 |