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had been, and where the soufriere is now, I found a chasm or crack, in the mountain, which seemed to have been a crater, but which had been closed by some convulsion, where, by the removal of the middle, the sides had been impelled together with such force, as to break up the walls, and leave the whole in the greatest confusion. The fumerols are on the side of this crack, without any accumulation of sulphur, or alum rock, for these substances fall into the crack as fast as they are formed. The scenery is exceedingly rugged and wild; the rocks broken in immensely large masses, and irregularly thrown about in every direction. At the northern extremity of this crack lies what is called the cave, whence there issued about fifteen or twenty years ago, a flood of water and stones, which ran down the valley, at present called the valley of Faujas, in the utmost disorder. I am inclined to think that water only came from the crack, and that it ran over the mountain, sweeping in its course all the small stones and cinders, leaving those that were too large to be moved. This irruption of water was cool, and without any apparent connection with heat, though it was most probably ejected by the force of some elastic fluid.
Montserrat. I passed close to the leeward side of the island of Montserrat, but did not land. The south side had an appearance of being partly composed of solid rock, and the rest of the island might be supposed to be constituted of cinders mixed with loose rocks, as it consists of one mountain, the sides of which are furrowed by the rain, gently, and not in precipices, as would have been the case had there been many currents of solid lava, which circumstance, with the flatness of the coast, and the gradual ascent of the mountain, would seem to indicate a great proportion of cinders.
Nevis consists of one mountain in the middle, a truncated cone, I suppose about 2000 feet high; and one small elevation to the south, called Saddle-Hill, and another to the north called Roun l-Hill; the rest of the island is a gradual descent from these three hills to the sea. It is composed of large masses of rocks, and beds of cinders, gray, red, and black, of various degrees of solidity, from the pumice to the compact lava; the black crystals I take to be augite, or perhaps what
Werner calls the basaltic hornblend of the Cape de Gate in Spain, many of the rocks being like those found at that place. The white or glassy I take to be feldspar, which, with a black substance resembling hornblend, constitutes a great proportion of the rocks of the volcanic islands in the West Indies. The nodules which are found occur more frequently in the centre of other rocks, they are of a small compact grain like greenstone, and not unlike those rounded pieces found in granite.
About one mile and a half S. E. of Charleston, there is a soufriere almost extinct, which occupies about two or three acres of a level spot. One mile below, there is a hot spring, the water of which rises to 110 degrees of Fahrenheit, and is used as a medical bath; and on the edge of the sea, about half a mile distant, the heat of the earth is sufficient to make the water boil. To the north of Charleston there are likewise soufrieres, and there can be little doubt that on all the islands, there have been a number of soufrieres which are now extinct and wasted away.
St. Christopher. This island, near Basseterre, consists of beds of black, red, and gray cinders, varying in thickness from two inches to many feet, containing black and white crystals, resembling those found in the last cinder eruption of St. Vincent. The sand on the bay of Bassetere is mostly of the black iron kind, with scarcely any of the broken shells or madrepore rock. Along the coast to Old-Road, the formation is of cinders, with few detached rocks, and the same from Old-Road to Brimstone-Hill.
Brimstone Hill is a stratification of madrepore limestone, containing shells, at an angle of upwards of 50 degrees from the horizon, reposing upon a bed of volcanic cinders, and partly covered by volcanic eruptions, making a fine specimen of the alternation of the Neptunian and volcanic formation, which, for aught we know, may be repeated twenty or thirty times in the foundation of these islands, as every current of lava that runs into the sea is liable to be covered with corals, madrepores, &c. and afterwards recovered with lava, until it comes above the surface of the sea.
On the south end, above Sandy Point, there is more pumice.
stone, and at a point a little north there appear to be solid masses of compact rock, which look like currents of lava. From Sandy Point to Deep Bay, the rocks which occur are those mixed with cinders of a black colour, and full of glassy or transparent crystals.
St. Eustatia is formed of two hills that appear to have been both craters of volcanoes; the western one is more ancient, and is filled up with earth, &c.; the eastern one is higher, and appears to be more recent, the crater being only partially filled. The space between these two hills is filled with cinders, forming a plain with a bay on each side; the one to the leeward is the harbour, on the edge of whieh stands the town.
On the south-east side of the large hill, towards St. Christopher, there is a stratification of madrepore limestone, alternating with beds of shells, similar to those found at present in the sea. The whole of this marine deposition dips to the southwest at an angle of upwards of 45 degrees from the horizon, resting upon a bed of cinders, full of pumice and other volcanic rocks, and is immediately covered by a bed of madrepore, sand and cinders, mixed together, with blocks of volcanic rocks so disseminated that there can be no doubt of the volcanic origin of the substance above and below the maprepore rock, which may be from five to six hundred yards thick. Part of this madrepore rock is changed into silex, having the part. that surrounded the animal converted into chalcedony. A considerable quantity of gypsum is found near the same place, in a crystalline state.
Saba. This little island seems to finish the volcanic formation, and consists of one mountain, rather rougher and more rugged than St. Eustatia, but apparently of nearly the same kind of rocks.
The foregoing description of the volcanic islands may perhaps authorize the following general remarks.
1st. That there is a great similarity in the substances ejected, which are marked by a family feature running through all the rocks, cinders, &c. of the different islands; and it is to be observed that the proportion of cinders, pumice, and other
light substances, is much greater than of the solid lavas, which are but thinly scattered; also that the cinders are always the lowest stratum on a level with the sea; and the masses of solid lava, near that level, repose on a bed of cinders, in every place where I had access to them.
2d. The madrepore and coral rocks, mixed with shells, partly similar to those found at present in the sea, are found in many places alternating with the cinders, and other volcanic rocks, presenting much the appearance of the whole having been ejected from the bottom of the ocean.
3d. The direction of the islands, running from north to south, a little easterly, corresponds with the direction of the strata of those stratified islands, lying to the eastward: such as Barbadoes, St. Bartholomew, &c. which should seem to support the supposition, that the seat of combustion occupies a stratified substance, running parallel to the general stratification of the surrounding rocks.
4th. In all the islands there are one or more soufrieres, all of which form alum rocks, and deposit sulphur, proving that sulphur is one of the ingredients that support the combustion. and perhaps giving strength to the supposition, that whatever may have been the original cause of the combustion, that cause is uniform, and the same through all the islands.
5th. In the late eruption of cinders, there was a great quantity of stones thrown out, exhibiting no appearance of having ever been in a state of fusion, but only roasted by a considerable heat; most of these rocks have every appearance of belonging to the primitive class, by their crystalline structure, and the position of their component parts: from which it would appear reasonable that the following conjectures may be hazarded.
1st. That the islands were probably thrown up from the bottom of the ocean.
2d. That the seat of combustion is more probably in a substance stratified, and that sulphur is one of the combustible ingredients.
3d. That the substance so stratified is most probably
primitive, and that consequently the combustion is in the primitive region covered by the transition, which forms the islands of the eastern group.
ART. XVI. On the original Formation of the Arabic Digits.
ADMITTING the probability of the conjectures of the author of the third article in No. II, respecting the original formation of the Arabic digits," 1, 2, 3, 4, 5, 6, 8, 0, founded on the data there premised, may we not suppose it more likely that the Arabians would have formed the remaining digits, from different compounds of the inferior numbers, rather than that they would have gone aside (according to the hypothesis of the author of Art. 19, No. III) and have had recourse to the Greeks for the formation of 7, and 9, or have substituted the Greek figures for their own, on account of the supposed awkwardness of their compositon? For as the conjectures of the author of Art. 3, respecting the formation of 2, 3, 4, 5, 6, and 8, cannot but be admitted as very ingenious, and the remaining two digits may be formed after a similar manner, is it not much more reasonable to assume, that they were all formed after the same method? otherwise we are left to institute the enquiry, on what sufficient grounds the Arabians should have borrowed from the Greeks the formation of those two digits, when they could have formed them themselves with as much ease as they had formed any of the others.
Having been but lately become acquainted with the Journal of Science, &c. after the perusal of Art. 3, No. II, and Art. 18, No. III, it cccurred to me, that the following would be the original formation of the digits in question, 7, and 9, following the plan proposed in Art. 3.
7, is first a perpendicular I, which with a straight line making a right angle with this perpendicular, becomes
and with the addition of a line parallel to the first line is 7