Narrative of the Circ.u.mnavigation of the Globe by the Austrian Frigate Novara.

Volume I.

by Karl Ritter von Scherzer.

PHYSICAL AND GEOGNOSTIC SUGGESTIONS,

BY

ALEXANDER VON HUMBOLDT.

In compliance with the gracious invitation which H.I.H. the Archduke Ferdinand Maximilian was pleased to address to me from Trieste (December 12th, 1856), and as yet barely recovered from an indisposition, I jot down these hasty notes, without presuming to give definite instructions, such as those I drew up, conjointly with M. Arago, for the guidance of the French expeditions, or for Lord Minto, then First Lord of the Admiralty, on the occasion of the Antarctic Voyage of Discovery of Sir James Ross (1840-43). The following pages consist simply of hints which may possibly prove serviceable to the distinguished and highly informed gentlemen, who have the good fortune to sail on board the Imperial Frigate, _Novara_, under the command of Commodore von Wullerstorf. With two of these savans, Dr. Ferdinand Hochstetter and Dr. Karl Scherzer, I have had the pleasure, here in Berlin, to agree verbally on various subjects.

As I do not exactly know what course it is intended the _Novara_ shall follow in navigating the Atlantic, nor in what meridian it is proposed to cross the Equator, (in conformity with the sound and useful directions of my friend Lieut. Maury, of Washington), on her voyage to Rio de Janeiro, nor how near she shall keep to Cape San Roque and Fernando de Noronha, I must content myself with inviting the attention of the voyagers in a general way to the temperature of the sea, as also to the variations and aberrations of the magnetic curves, and their currents.

A lower degree of temperature is usually observed W. of the Canaries, and Cape Verde Islands, commencing with the Salvages, the thermometer indicating as low as 727 Fahr. This has been already ascertained by Mr.

Charles Deville, in his chart of temperature on the voyage "aux Antilles, a Teneriffe et a Fogo." I consider this diminution of temperature results from the North Guinea current, bringing with it cold water from the north southwards as far as the Bight of Biafra and the River Gaboon, at which point it is encountered by an opposite current flowing northwards along the south-western coast of Africa from Loando and Congo.

In 1825, Captain Duperrey had accurately laid down the point of intersection of the magnetic, with the terrestrial equator. In 1837, we learned from Sabine's investigations of magnetic inclination near the Island of St. Thomas (on the Equator, adjoining the above portion of the coast of Africa), that this point of intersection had already shifted four degrees to the westward. A period of twenty years having elapsed since Sabine's expedition for determining observations with the pendulum, it would be most desirable that fresh investigations should be made in that neighbourhood, for the purpose of verifying the secular changes of all magnetic curves, especially with regard to their variation. In 1840, the line of no declination in America began 9 30' E. of South Georgia, whence it ran to the S.E. coast of Brazil, near Cape Frio, thus traversing the mainland of South America only between the latter point and the parallel of 0 36' S., when it leaves the continent a little to the east of Gran Para, near Cape Tigioca, cutting the terrestrial equator again, but in 50 6' W. According to Bache's Map of Equal Magnetic Declination, it reaches the coast of North America near Cape Fear, to the south-west of Cape Lookout. This line, along which the magnetic declination is _nil_, extends to a point in Lake Erie, 2 40' W. of Toronto, where the declination is already 1 27' W.[2]

[Footnote 2: Wherever, in this paper, it is not precisely expressed to the contrary, the scale of the Centigrade Thermometer, the longitude from the Meridian of Paris, the French foot (_pied du roi_=1279 inches English), and the geographical mile, 15 to a degree of the Equator, measuring 3807 "toises," are meant.]

It is evident from the observations of Captains Beechey and Findley, and still more particularly from those of the French Captain Kerhallet, that the remarkable subdivision of the main equinoctial current, flowing from east to west into two branches, one directed to the N.W., the other to the S.S.W., commences at a considerable distance from the Capes of St. Roque and St. Augustin. This bifurcation has always, and with good reason, been ascribed to the protruding convexity of the South American continent at these two promontories. It would be an important step gained in verifying the theory of currents, could the precise distance be ascertained by chronometer. It is apparently like an "_actio in distans_," probably a phenomenon of what is known as "packing." As the frigate, on leaving Rio de Janeiro is to make for the Cape of Good Hope, the opportunity will present, should she steer sufficiently southerly, for many interesting observations with respect to the _connecting current_ W.N.W. and E.S.E.

which encounters that from Madagascar and Mozambique, close to the Cape, more especially with regard to the temperature of the sea.

If the frigate is intended to approach the small cl.u.s.ter of islands of Fernando de Noronha, E. of Pernambuco (Lat. 3 50' S.), I would recommend to that excellent geognostic, Dr. Hochstetter, the hornblendic phonolithe rock found there, far from a volcanic crater, but with trachytic d.y.k.es and basaltic amygdaloid. The flat little island of St. Paul (Penedo de San Pedro), 1 N. Lat., singular to say, is not volcanic at all, containing, like the Malouin or Falkland Islands, slaty green-stone pa.s.sing into serpentine.

Should the frigate alter her course and cross the Equator more to the eastward, without touching at Rio de Janeiro, she might possibly fall in with the Marine Volcanic region, (Lat. 0 20' S., Long. 22 W.), which has quite lately become famous again by the U. S. Expedition of the Brig _Dolphin_ (1854), commanded by Lieutenant Lee. On 19th May, 1806, columns of black smoke were seen issuing from the sea by Krusenstern, and volcanic ashes were gathered, after a singular bubbling of the sea from 1748 to 1836, according to careful investigations by Daussy.

As the frigate is commissioned to visit Ceylon and the Nicobar Islands, she cannot sail direct from the Cape to Australia; and the hope must therefore be abandoned of her visiting the small basaltic islands, known as Prince Edward's (47 2' S., 38 E.), and Possession (46 28' S., 47 30' E.), belonging to the Crozet's Group, or the two islands, long confounded with each other, of Amsterdam (Lat. 37 48' S.) and St. Paul (Lat. 38 38' S.) The latter island, the more southerly of the two, (a very characteristic drawing of which was given by Willem de Vlaming so far back as 1696), is supposed to be volcanic, not only by its form, which will at once remind the geologist of Santorin, Barren Island, and Deception Island, (one of the New Shetland group), but also in consequence of the eruption of steam, and the flames occasionally observed there.

As for Amsterdam, which consists of a single densely-wooded mountain, the puzzle remains for solution as to how, during the expedition of D'Entrecasteaux in 1792, the whole island seemed, during two entire days, enveloped in smoke; whereas, on landing there, the naturalists of that expedition were satisfied that the mountain was not an active volcano, and that the columns of steam issued out of the ground near the sh.o.r.e! As yet, the phenomenon remains entirely unexplained.

If we examine any map of the Indian Ocean, we may trace the continuation of the Sunda group from Sumatra, N.W., through the Nicobar, and Great and Little Andaman Islands, and thence through the volcanoes of Barren Island, Narcondam and Cheduba, nearly parallel with the coasts of Malacca and Tena.s.serim, all on the eastern part of the Bay of Bengal. The minor volcanoes just enumerated will present valuable opportunities of geological enquiry.

Along the coasts of Orissa and Coromandel, the western portion of the Bay of Bengal is quite free of islands, Ceylon, like Madagascar presenting rather the type of a continent.

Off the W. coast of the peninsula of India, (that is opposite the Neilgherrie hills, and the coast of Canara and Malabar), there is a series of three archipelagoes, extending from 14 N. to 8 S., viz., the Laccadives, the Maldives, and the Chagos, which appears, as it were, continued through the banks of Sahia di Malha, and Cargados Carajos, to the volcanic group of the Mascarenhas and Madagascar. As the first-named archipelagoes, so far as is yet known, consist solely of coral, and are, consequently, true "atolls," or reef-lagoons, the bottom of the ocean should be examined over a large extent, adopting the ingenious hypothesis of Darwin, that it is to be considered _as an area of subsidence_, rather than an elevated region.

It would also be a matter of great importance to get observations respecting terrestrial magnetism, particularly so as to define the position of a given segment of the magnetic equator. Capt. Elliott, as the result of his comprehensive studies, (1846-49), ascertained that the magnetic equator pa.s.ses through the north end of Borneo, and thence nearly due W. to the northern extremity of Ceylon. In this region the curve of minimum intensity is nearly parallel to the magnetic equator, which intersects the Continent of Africa near Cape Guardafui--according to Rochet d'Hericourt, in lat. 10 7' N., long. 38 5'. E. Between this point and the Bight of Biafra nothing is known.

The South Asiatic islands comprise Formosa, the Philippines, the Sunda group, and the Moluccas. The great and little Sunda Islands and the Moluccas embrace 109 volcanoes, with fiery eruptions, and 10 what are called mud-volcanoes. This is not a mere estimate, but is the result of an enumeration by Junghuhn, who, within the last year (1856), has returned to Java, and thoroughly equipped by M. Pahud, Governor-General of the Indian Netherlands, will be of great a.s.sistance to the Imperial Expedition.

An exact mineralogical determination of the volcanic rocks (trachytes) is unfortunately wanting everywhere.

The most active volcano of Sumatra is the Gunung Merapi (8980 feet), which must not be confounded with a volcano in Java, of the same name. That of Sumatra was ascended by Dr. L. Horner, and Dr. Korthals in 1834. We may p.r.o.nounce Indrapura (11,500 feet, but this measurement is very uncertain), and Gunung Pasoman (9010 feet), the Ophir of our maps, to be utterly unknown geologically. The highest of the Java volcanoes is Gunung Semeru (11,480 feet), ascended by Junghuhn in 1844, 1220 feet higher than the Etna. The largest craters of the 45 which are disposed in a line along the sh.o.r.es of Java, are Gunung Tengger, and Gunung Raou. Dr. Junghuhn has recently given the outlines of each separate volcano in his splendid topographical and geological map of Java, in four sheets, published in 1856, which does great credit to the Dutch Government.

The following subjects are worthy of special attention while the frigate is at Java.

1. The curious phenomenon of the ribbed surface. (_Vide_ Junghuhn, Java, Part II., p. 608.)

2. The disposition, as yet unaccounted for, of a series of regularly-shaped hills, formed by the mud-streams ejected in the year 1822 by the volcano of Gunung Galungung. (_Vide ut supra_, pp. 127-731.)

3. The ejection of water by the Gunung Idjen, on 21st January, 1817, (pp.

707, and 717-121).

4. The erroneousness of the a.s.sertion that the volcanoes of the Island of Java do not emit streams of real lava.

It must be admitted that the mighty Javanese volcano, Gunung Merapi, already alluded to, has not, within the historic period, presented any coherent compact streams of lava, but mere fragments and boulders; although in 1837, lines of fire were seen running uninterruptedly from the top down the sides of the cones in eruption. But each of the three volcanoes, Tengger, Idjen, and Slamat, present examples of black lava currents, descending as far as the tertiary strata.

Streams of stone-boulders, red-hot, similar to those of the Cotopaxi, but scarcely touching each other, flowed from Gunung Lamorgan on 6th July, 1838.

No active volcano is known in the island of Borneo. The highest mountain of the whole island, perhaps of the whole insular world of Southern Asia, is the Hina Balu (12,850 feet?) on the northern point of Borneo. It is as yet unexplored. According to Dr. Lewis Horner, son of the astronomer of the Krusenstern expedition, there occur among the syenite and serpentine mountain range of Rathus, on the S.E. of the island, deposits yielding gold (which has even been worked by diggings), diamonds, platinum, iridium, and osmium,--presenting, in fact, a similar a.s.sociation to those of the Ural mountains. No mention is made of palladium. Rajah (now Sir James) Brooke describes in the province of Sarawak in Borneo, a low hill, Gunung Api ("hill of fire" in Malay), the slags of which attest former volcanic activity. A visit to Borneo would be of very great service.

There are eleven volcanoes in Celebes, and six in Flores, all active.

It is still uncertain whether the conical mountain Wawari, or At.i.ti, which is more generally known as the volcano of the island of Amboyna, ever poured out anything except hot mud (1674), or whether it should be merely cla.s.sed as a _solfatara_. The main group of the South Asiatic Islands is connected through the Moluccas and the Philippines with the Papua and Pellew islands, and the Caroline Archipelago of the South Sea.

The most important geological fact to be remarked with reference to the island of Formosa, abounding in mineral coals, is the break in the line of direction of the open vents, when, instead of N.E. to S.W., the central line follows the meridian line, which it pursues nearly as far as 6 S., pa.s.sing through Formosa and the Philippine Islands (Luzon and Mindanao), respecting which deviation nothing certain is known, and in which region every mountain of conical shape, or outline is invariably set down as a volcano, even though there should be no indications of a crater. The Sooloo Archipelago forms the connecting link between the islands of Borneo and Mindanao, the long, narrow island of Palawan, const.i.tuting that between Borneo and Mindoro.

The Island of Yesso, separated from that of Niphon by the Straits of Sangar, or Tsugar, and from the islands of Krafto (Saghalien) and Tschoka, or Tarakai, by the Straits of La Perouse, connects, through its North Eastern Cape, with the archipelago of the Kuriles. From Broughton's Southern Vulcan Bay up to its northernmost point, Yesso is traversed by an uninterrupted range of volcanoes--a fact the more worthy of being recorded, as in the expedition of La Perouse there were found red porous lavas, as well as wide areas, covered with slags, in the Baie des Castries, in the narrow island of Krafto (Saghalien), which is, as it were, merely a continuation of Yesso. In our own day these regions command a higher interest, from a political point of view, more especially since Russia, dissatisfied with the situation of Okhotsk, at the sanded mouth of the Amoor, was anxious, after the destruction of Petropaulowski, on the coast of Kamtschatka, to obtain, on the S.E. coast, a harbour suitable for a military station.

Among the three islands which form the main portion of the j.a.panese Empire, six volcanoes are known to have had eruptions in the historic period. The volcano, Fusi Jama, in Niphon, province of Suruga (Lat. 35 18' N., Long. 136 15' E., alt.i.tude 11,675 feet), is said to have risen out of the plain 286 years before the Christian era. Its last eruption was in 1707. The volcano, Asama Jama, in the district of Saku, between the meridians of the two capitals, Miaco and Jeddo, was last in eruption in 1783. On the island of Kiusiu, adjoining the peninsula of Corea, four volcanoes are situated, from one of which, called Wanzen, there was a most destructive eruption in 1793.

The beautiful work of Commodore Perry, U.S.N., detailing his mission to j.a.pan, on the part of the United States Government, in 1852, containing excellent photographs of races, as also drawings by the Berlin artist, Wilhelm Heine, does not, as yet, comprise the scientific results of that expedition.

Proceeding northwards, the volcanoes are more densely crowded, and are found arranged in series. Of the fifty-four which I enumerated as still in activity among the islands of Eastern Asia, there are thirty-four on the Aleutian, and ten on the Kurile Islands. The Peninsula of Kamtschatka contains nine volcanoes, which have been in activity within the historic period. Lying under the 54th and 60th degrees of northern lat.i.tude, we see a long strip of sea-bottom between two continents undergoing a perpetual process of destruction and re-arrangement.

The South Sea, the superficial extent of which is one-sixth greater than that of the entire solid crust of our planet, actually presents a smaller number of active volcanoes, less vents for communication between the centre of the earth and its atmospheric envelope, than the single Island of Java! Out of 40 volcanic cones, including those which are extinct, only 26 have been seen in eruption during the historic period. They are not scattered at random, but, on the contrary, as was pointed out by Mr. James Dana, the ingenious geologist of the great United States Exploring Expedition, under the command of Capt. Wilkes (1838-42), they have been thrown up, at widely extending clefts, communicating by submarine mountain systems. They are arranged in groups and distinct regions, a.n.a.logous to the mountain chains of Central Asia and Armenia (in the district of the Caucasus), and belong to two quite distinct systems, one running S.E. to N.W., the other S.S.W. to N.N.E.

In the Hawaiian Archipelago (or Sandwich Island group), we find Mauna Loa, according to Wilkes, 12,900 feet in height, which does not present any cone of volcanic scoriae (resembling, in this particular, the volcanoes of the Eifel), but has emitted streams of lava. The lava basin of Killauea, 13,000 feet in its greatest, by 4800 in its smallest diameter, is not a _solfatara_, but a true lateral vent on the flank of the powerful Mauna Loa itself, exactly resembling the less elevated sheet of lava of Arak.

Mauna Kea is 180 feet higher than Mauna Loa, but is extinct. Tafoa and Amangura, in the Tonga group, are still in eruption, the last discharge of lava having occurred in July, 1847. The volcano of Tanna was in full eruption during Capt. Cook's Voyage of Discovery in 1774, as was also the volcano of Ambrym, west of Malicollo in the archipelago of the New Hebrides. At the south point of New Caledonia, lies Matthew's Rock, a small smoking rocky island. The volcano of Santa Cruz, N.N.W. of Tina Kora, with periodical eruptions occasionally occurring at intervals of 10 minutes, had been already noticed as a volcano by Mendana, so far back as 1595. In the Salomon Archipelago, there is found the volcano of Sesarga, while others are said to be in full activity in the Marianas or Ladrones, just like those of Guguan, Pagon, and El Volcan Grande de Asuncion, which appear to have broken forth along a line that follows the meridian. In New Britannia, three conical mountains were observed vomiting streams of lava, by Tasman, Carteret, and Labillardiere. There are two volcanoes in full activity on the north-east coast of New Guinea, opposite Admiralty Islands, which themselves are so rich in obsidian. In New Zealand, numerous regions abound in basaltic and trachytic rocks. Of active volcanoes there are Puhia-i-Wakati (the volcano of White Island), and the lofty cone of Tongariro (5816 feet). To the absence of centres of volcanic agency in New Caledonia, where sedimentary formations and seams of coal have recently been discovered, is ascribed the vast development of coral reefs. Dana was the first to ascend the Peak of Tafua, in the Island of Upolu, one of the Samoa group, not to be confounded with the still active volcano of Tafoa, south of Amangura, in the Tonga Archipelago. Dana found in it a crater overgrown with thick forest. So, too, on the isolated Vaihu or Easter Island group, there is found a range of conical mountains with craters, but inactive.

Of the volcanic groups of the South Sea, the most violent is the farthest east, adjoining the sh.o.r.es of the New World, viz., the archipelago of the Gallipagos, which consists of five considerable islands, very admirably described by Darwin. There are streams of lava down to the very sh.o.r.e of the sea, but no pumice. Some of the trachytic lavas are said to abound with crystals of albite. It is important to examine whether or not this is oligoclase, as on Teneriffe, Popocatepetl, and Chimborazo; or labradorite, as on Etna and Stromboli. Palagonite, exactly similar to that of Iceland or in Italy, was discovered by Bunsen in the specimens of tufa from Chatham Island, one of the Gallipagos.

New Holland does not show any signs of recent volcanic activity, except at its most southern point (Australia Felix), at the foot of the Grampian Mountains. N.W. from Port Philip, as also towards the Murray River, there are numbers of volcanic cones and sheets or flows of lava.

It would be of great interest and utility to observe the relative inclinations of the Magnetic and the Geographical Equators, by means of the dip of the magnetic needle, though this will be rendered more difficult, from the fact of the ship's course being easterly, that is, contrary, to the Equinoctial current. As regards the low temperature of the current, which I discovered in 1802, running up from 40 S. to the Gallipagos along the coast of South America, and then turning westward, it would be highly important to investigate whether in the eastern part of the South Sea in 7 N. and between 117 and 140 W., there really exists in every season a _counter current_ from west to east. But I need not enlarge upon this topic to such attentive navigators.

The line of no inclination was crossed six times by Duperrey between 1822 and 1825. When I first discovered, near Truxillo, the low temperature of the cold Peruvian current, it was 128 Reaumur (608 Fahr.). The temperature observed in the course of twenty years by Mr. Dirckinck von Holmfeld, in the neighbourhood of Callao, expressed in degrees of Reaumur, were as follows:--

September 1802 128 (Fahr. 608) } Thermometer in the air.

November " 124 ( " 599) } 133 Reaumur.

December, end of 168 ( " 698) } (6192 Fahr.) January 1825 127 ( " 6057) February " 153 ( " 6642) March " 157 ( " 6732) April " 145 ( " 6462)

The temperature of the sea I found to be 22 Reaumur (815 Fah.) north of Cape Blanco, when on my way from Callao de Lima, at which point the cold current diverged towards the Gallipagos.