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Alexander von Humboldt: „On the Luminousness of the Ocean“, in: ders., Sämtliche Schriften digital, herausgegeben von Oliver Lubrich und Thomas Nehrlich, Universität Bern 2021. URL: <> [abgerufen am 31.01.2023].

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Titel On the Luminousness of the Ocean
Jahr 1828
Ort Edinburgh
in: The Edinburgh New Philosophical Journal (Juli–September 1828), S. 329–331.
Entsprechungen in Buchwerken
Alexander von Humboldt, Ansichten der Natur, Stuttgart und Tübingen: Cotta 1808, S. 219–226, Anmerkung 5.
Sprache Englisch
Schriftart Antiqua
Textnummer Druckausgabe: IV.89
Dateiname: 1828-On_the_Luminousness-1-neu
Seitenanzahl: 3
Zeichenanzahl: 5757

Weitere Fassungen
On the Luminousness of the Ocean (Edinburgh, 1828, Englisch)
Humboldt über das Leuchten des Meeres (Berlin, 1829, Deutsch)
Hafsvattnets lysande (Borgå, 1856, Schwedisch)

On the Luminousness of the Ocean.

The luminousness of the ocean is one of the most beautifulphenomena of nature, which excites surprise, although, formonths together, it may be seen every night. The sea is phos-phorescent in all latitudes; but he who has not witnessed thisphenomenon in the torrid zone, and especially in the PacificOcean, can form but an imperfect idea of the magnificence ofsuch a spectacle. When a vessel of war, impelled by a freshbreeze, cleaves the foamy waves, and one is stationed near theshrouds, he cannot be satisfied with viewing the beautiful phe-nomenon which presents itself. Every time that the side of theship, as she rolls, emerges from the water, flashes of reddishlight seem to issue from the keel, and dart toward the surfaceof the sea. Le Gentil* and the elder Forster , explained theappearance of these flashes by the electrical friction of the wateragainst the body of the advancing ship. But in the presentstate of our knowledge, this explanation is no longer admissible. There are few points of natural history respecting which therehave been so many disputes as the light emitted by the watersof the ocean. What we know with precision on the subject, re-duces itself to the following facts. There are various shiningmollusca which, during their life, emit at pleasure a rather weakphosphoric light, generally of a bluish colour. This is observedin the Nereis noctiluca, the Medusa pelagica, var. β, and the Monephora noctiluca, discovered during Captain Baudin’s expe-dition . Of this number are also the microscopic animals,which have not as yet been determined, and which Forster sawswimming in the sea in innumerable multitudes, near the Cape
* Voyage aux Indes, t. i. p. 685‒698. Observations made during a voyage round the world, 1683, p. 57. InGerman. Forskoe, Fauna Ægyptiaco-Arabica, p. 109. Bory St Vincent, Voyage aux Iles d’Afrique, t. i. p. 107, pl. 6.
|330| of Good Hope. The luminousness of sea water is sometimesoccasioned by these living lanterns. I say sometimes; for, inmost cases, notwithstanding the use of magnifying glasses, noanimal is perceived in luminous water; and yet, whenever thewave happens to strike a hard body and breaks, producing foam,and whenever the water is strongly agitated, a light is producedresembling a flash of lightning. This phenomenon probablyoriginates from the decomposed fibrils of dead mollusca whichexist in infinite quantity in the depths of the sea. When thisluminous water is passed through a piece of dense cloth, thesefibrils are sometimes detached from it under the form of lumi-nous points. When we bathed in the evening in the Gulf ofCariaco, near Cumana, some parts of our bodies remained lumi-nous on coming out of the water. The luminous fibres stuck tothe skin. From the immense quantity of mollusca dispersedthrough all the seas of the torrid zone, it need not be surprisingthat the water of the sea is luminous, even when no organicmatter can be separated from it. The infinite division of all thedead bodies of dagyses* and medusæ may render the entire seacapable of being considered as a gelatinous fluid, and which is inconsequence luminous, has a nauseous taste, cannot be drunk byman, but affords nourishment to many fishes. If a board berubbed with a part of the body of the Medusa hysocella, theplace rubbed becomes luminous whenever the finger, well dried,is passed over it. During my passage to South America, Isometimes put a medusa on a tin plate. If I struck the platewith another metal, the smallest vibrations of the tin were suf-ficient to make the animal shine. How did the blow and thevibration act in this case? Was the temperature instantaneous-ly raised? Were new surfaces uncovered, or did the blowmake the phosphuretted hydrogen gas escape, so that, cominginto contact with the oxygen of the atmosphere, or with the wa-ter of the sea, it produced combustion? This effect of the blowwhich excites the light is particularly striking in a jumbling sea,when the waves dash against each other in all directions. Be-tween the tropics, I have seen the sea luminous at all tempera-tures; but it was more so before storms, or when the sky was
* The genus Dagysa belongs to the Salpa tribe of Cuvier.
|331| lowering, cloudy, and much overcast. Cold and heat seem to havelittle influence upon this phenomenon; for, on the Bank of New-foundland, the phosphorescence is often very strong at the se-verest time of the winter. Sometimes, all other circumstancesappearing to be the same, the phosphorescence is very distincton one night, and the following night there is scarcely any.Does the atmosphere favour this disengagement of light, thiscombustion of phosphuretted hydrogen? Or do not these dif-ferences depend merely upon chance, which leads the navigatorinto a sea more or less filled with mollusca? Perhaps, also, theluminous animals only come to the surface of the sea when theatmosphere is in a certain state. M. Bory St. Vincent, askswith reason, why our fresh marsh-water, which is filled with po-lypi, is not luminous? It would appear in fact, that a particu-lar mixture of organic particles is necessary to favour this dis-engagement of light. Willow-wood is more phosphorescentthan oak. In England, salt-water has been rendered luminousby casting herring brine into it. Galvanic experiments shewthat the luminous state of living animals depends upon an irri-tation of the nerves. I have seen an Elater noctilucus, whichdied, diffuse a strong glow when I touched its anterior extremi-ties with tin or silver. Sometimes, also, the medusæ give out astronger light at the moment when the galvanic chain is closed. Humboldt, Tableaux de la Nature, tom. ii. p. 80‒87.