Miscellany — May 2010

Volcanoes: the good, the bad and some science

Volcano erupts in south Iceland
The volcano near Eyjafjallajoekull glacier began to erupt just after midnight, sending lava a hundred metres high. . . . A state of emergency is in force in southern Iceland and transport connections have been severely disrupted, including the main east-west road.

— BBC News 12:23 GMT, Sunday, 21 March 2010

. . . of course it wasn't just the island's "main east-west road" that was disrupted — by 14 April, the eruption had closed nearly all airspace in Europe.

EE's correspondents didn't need to worry about disruptions to their discount holidays, business meetings in New York, or the supply of fresh flowers from Kenya. Still they were fascinated by vulcanism, and volcanoes were an attraction on the Tour — whether one saw them as horrors or as the natural sublime; lessons were to be drawn, too, from the archeological remains hidden and preserved by their fiery tempers. And one could depend on a good volcano to provide a commanding metaphor for one's fellow correspondents. Amongst all this, it was even possible to find a remarkable degree of subtle knowledge on how the whole planetary process worked — here reported in a poetic review.

June 1740: Thomas Gray on the streets of Portici

On the 24 August 79 CE, two months after the death of the emperor Vespasian, Vesuvius erupted and (as every school-child knows) buried the towns of Pompeii and Herculaneum. But the English poet Thomas Gray, writing an epistolary travelogue to his mother in spring 1740, reminds us that they were not the only towns to suffer. While at Naples, Gray reports having visited

. . . the Sybils' cave and many other strange holes under ground . . .; but the strangest hole I ever was in, has been to-day at a place called Portici, where his Sicilian Majesty has a country-seat.

Vesuvius from Portici, c. 1774–1776, by Joseph Wright (1734–1797)
Copyright ©2010 National Gallery of Art, Washington, DC

About a year ago, as they were digging, they discovered some parts of ancient buildings above thirty feet deep in the ground: Curiosity led them on, and they have been digging ever since; the paſsage they have made, with all its turnings and windings, is now more than a mile long. As you walk you see parts of an amphitheatre, many houses adorned with marble columns, and incrusted with the same; the front of a temple, several arched vaults of rooms painted in fresco. Some pieces of painting have been taken out from hence, finer than any thing of the kind before discovered, and with these the King has adorned his palace; also a number of statues, medals, and gems; and more are dug out every day. This is known to be a Roman town, that in the Emperor Titus's time was overwhelmed by a furious eruption of Mount Vesuvius, which is hard by. The wood and beams remain so perfect that you may see the grain; but burnt to a coal, and dropping into dust upon the least touch.

— EE letter id: graythOU0010162a1c

August 1773: Hamilton & Walpole / Voltaire & Vesuvius

Probably best known today for being cuckholded by Admiral Nelson, Sir William Hamilton (British Envoy Extraordinary and Plenipotentiary to the Court of Naples) was also an amateur volcanologist and author of Observations on mount Vesuvius, mount Etna, and other volcanos (London, 1772). The volume attracted widespread attention and drew a remarkable letter from Voltaire (17 June 1773), comparing the "eternal calm" of the Alpine "mountains of ice" (visible from Voltaire's own windows at Ferney) to the "too hot-tempered. . . little men" of Vesuvius and Etna:

Les montagnes, que vous avez vues de mes fenêtres à Ferney, sont dans un goût tout opposé. Votre Vésuve, et votre Etna sont pleins de caprices; ils ressemblent aux petits hommes trop vifs qui se mettent souvent en colère sans raison. Mais nos montagnes des glacières qui sont dix fois plus hautes et quarante fois plus étendues, ont toujours la même physionomie , et sont toujours dans un calme éternel.

— EE letter id: voltfrVF1240026b1c

Hamilton seems to have passed the letter to Horace Walpole, for the latter writes from Strawberry Hill in August, commenting in shades of magenta on Voltaire's lilac prose:

I am always glad to see Voltaire’s letters; but much more when they procure me one from you, whom I love much better, & without a Draw-back. There is spirit in his letter, it is true, but while he is contesting Volcanos, his thoughts seem to have been blown up by the explosion of one. It looks as if his head had fallen to pieces on a sheet of paper, & that his Ideas had tumled out higgledy piggledy. . . . We folks of old-fashioned understandings look on burning Mountains as very petulant ovens, & a little destructive. The modern French Philosophers seem to have a mind to make them Parents of Order, & a kind of Providence, as far as they will admit any.

— EE letter id: voltfrVF1240095a1c

October 1785: Bentham on Etna & Sicily, as the world shrinks to his compass

On 11 October 1785, aboard the Mary Frances on his way to join his brother Samuel in Russia, Jeremy Bentham recorded the ship's passage through the Straits of Messina. The threat of bad weather meant a slackening of sails and a calmer stomach for Bentham (he had been sea-sick since leaving Livorno) as they skirted Sicily at a pace conducive to contemplation. Never one to dodge a chance to draw generalized conclusions from a passing observation, we find him reassuring himself (if reassurance he needed) that the world was shrinking to his compass:

As for Etna we have seen it in three several directions from so many different sides of the Island . . . . The side which fronts you as you approach the island from the gulph of Genoa is that from which Etna is at the farthest distance, yet though the sea is skirted all long with lofty mountains, Etna is plainly seen on the other side overtopping them all. When an observation by a quadrant shew'd it at 66 miles distance, we could plainly see the smoke issuing from it in torrents . . . . Considering how large an island Sicily is, how many mighty states it contained in classic times, and how considerable a figure it still makes on the map, I could not help wondering to observe that by far the greater part of it if not the whole could be taken by the eye not only in the course of one day's navigation, but in great measure at one view. From this and other specimens that have occurred in the course of this short part that has already elapsed of our short navigation our little globe has lost a vast deal of the space that it had been used to fill in my conception.

— EE letter id: bentjeOU0030371a1c

March 1793: William Cowper on the "Central Fires" of Darwin's grandfather

Erasmus Darwin, grandfather of the now more famous Charles, was not only a physician but a scientist, physiologist, abolitionist, inventor and poet. In 1791 he published a wide-ranging celebration — in verse — of much of contemporary science, entitled The Botanic Garden. The poem is in two parts: "The Economy of Vegetation" celebrates technological innovation and scientific discovery, and offers theories on contemporary scientific questions; "The Loves of the Plants" illustrates (and revises) the Linnaean scheme of botanical classification. Each part is divided into cantos with multiple "arguments", all with exhaustive authorial annotations explaining the science behind the poetry.

The first part of the Garden was reviewed in 1793 by the English poet William Cowper. Nearly half the review is concerned with the annotations — those instances of "philosophical knowledge, and ingenious speculation" — to Darwin's presentation of the "Central Fires" in the first canto:

III. NYMPHS! YOUR fine forms with steps impassive mock
Earth's vaulted roofs of adamantine rock;
Round her still centre tread the burning soil,
And watch the billowy Lavas, as they boil;
Where, in basaltic caves imprison'd deep,
Reluctant fires in dread suspension sleep;
Or sphere on sphere in widening waves expand,
And glad with genial warmth the incumbent land.

— The Botanic Garden (London, 1791: Part I, Canto 1, lines 137–144).

Darwin provides a philosophical annotation for line 139:

Round the still centre. l. 139. Many philosophers have believed that the central parts of the earth consist of a fluid mass of burning lava, which they have called a subterraneous sun; and have supposed, that it contributes to the production of metals, and to the growth of vegetables. . . .

— The Botanic Garden (London, 1791: Part I, Canto 1).

Cowper gives a detailed account of the scientific theory, along with a long list of the evidence gathered to support this belief in the Earth's central fires, including:

1. a paper by the French physicist Jean Jacques Dortous de Mairan (1678–1771), published in the Histoire de l'Academie de Sciences (1765), in which Mairan "endeavoured to shew that the earth receives but a small part of the heat which it possesses, from the sun's rays, but is principally heated by fires within itself";
2. "experiments made some years ago by Dr. Franklin, the spring-water at Philadelphia appeared to be of 52º of heat, which seems further to confirm this opinion, since the climates in North America are supposed to be colder than those of Europe under similar degrees of latitude";
3. "Mr. De Luc in going 1359 feet perpendicular into the mines of Hartz on July 5th, 1778, . . . found the air at the bottom a little warmer than at the top of the shaft. Phil. Trans. Vol. LXIX. p. 488;
4. "The very distant and expeditious communication of the shocks of some great earthquakes. The earthquake in Lisbon in 1755 was perceived in Scotland, in the Peak of Derbyshire, and in many other distant parts of Europe. The percussions of it travelled with about the velocity of sound, viz. about thirteen miles in a minute. . . . These phenomena are easily explained if the central parts of the earth consist of a fluid lava, as a percussion on one part of such a fluid mass would be felt on other parts of its confining vault, like a stroke on a fluid contained in a bladder, which however gentle on one side is perceptible to the hand placed on the other; and the velocity with which such a concussion would travel would be that of sound, or thirteen miles in a minute."
5. "The variation of the compass can only be accounted for by supposing the central parts of the earth to consist of a fluid mass, and that part of this fluid is iron . . . ."

— EE letter id: cowpwiOU0050100a1d

Although Cowper doesn't comment further, the next lines of the poem bring us full circle as Darwin moves from subterranean fires to vulcanism proper:

YOU from deep cauldrons and unmeasured caves
Blow flaming airs, or pour vitrescent waves;
O'er shining oceans ray volcanic light,
Or hurl innocuous embers to the night.—
While with loud shouts to Etna Heccla calls,
And Andes answers from his beacon'd walls;
Sea-wilder'd crews the mountain-stars admire,
And Beauty beams amid tremendous fire.

— The Botanic Garden (London, 1791: Part I, Canto 1, lines 149–156).

The reference to Mt Hekla returns us to Iceland, while Darwin's annotation shows him conflating the workings of geysers and volcanoes:

Hurl innocuous embers. l. 152. The immediate cause of volcanic eruptions is believed to be owing to the water of the sea, or from lakes, or inundations, finding itself a passage into the subterraneous fires, which may lie at great depths. This must first produce by its coldness a condensation of the vapour there existing, or a vacuum, and thus occasion parts of the earth's crust or shell to be forced down by the pressure of the incumbent atmosphere. Afterwards the water being suddenly raised into steam produces all the explosive effects of earthquakes. And by new accessions of water during the intervals of the explosions the repetition of the shocks is caused. These circumstances were hourly illustrated by the fountains of boiling water in Iceland, in which the surface of the water in the boiling wells sunk down low before every new ebullition.

Besides these eruptions occasioned by the steam of water, there seems to be a perpetual effusion of other vapours, more noxious and (as far as it is yet known) perhaps greatly more expansile than water from the Volcanos in various parts of the world. As these Volcanos are supposed to be spiracula or breathing holes to the great subterraneous fires, it is probable that the escape of elastic vapours from them is the cause, that the earthquakes of modern days are of such small extent compared to those of antient times . . . .