525 



SCIENTIFIC SIDE-LIGHTS 



Phenomena 

 Photography 



proportion of deep-sea animals seems to 

 prove that the phosphorescent illumination 

 is not universally distributed, and that there 

 must be some regions in which the darkness 

 is so absolute that it can only be compared 

 with the darkness of the great caves. 

 HICKSON Fauna of the Deep Sea, ch. 2, p. 

 27. (A., 1894.) 



2588. PHOSPHORESCENCE OF THE 

 OCEAN Porpoises Swimming in Paths of 

 Light. Standing at the bow and looking 

 forwards, at a distance of forty or fifty 

 yards from the ship, a number of luminous 

 streamers were seen rushing towards us. 

 On nearing the vessel they rapidly turned, 

 like a comet round its perihelion, placed 

 themselves side by side, and in parallel trails 

 of light kept up with the ship. One of them 

 placed itself right in front of the bow as a 

 pioneer. These comets of the sea were joined 

 at intervals by others. Sometimes as many 



^ as six at a time would rush at us, bend with 

 * extraordinary rapidity round a sharp curve, 

 and afterwards keep us company. I leaned 

 over the bow and scanned the streamers 

 closely. The frontal portion of each of them 

 revealed the outline of a porpoise. The rush 

 of the creatures through the water had 

 started the phosphorescence, every spark of 

 which was converted by the motion of the 

 retina into a line of light. Each porpoise 

 was thus wrapped in a luminous sheath. 

 The phosphorescence did not cease at the 

 creature's tail, but was carried many por- 

 poise-lengths behind it. TYNDALL Frag- 

 ments of Science, ch. 6, p. 149. (A., 1897.) 



2589. - 'Radiance from 



Death. Sometimes one cannot, even with 

 high magnifying powers, discover any ani- 

 malcules in the luminous water; and yet, 

 wherever a wave breaks in foam against 

 a hard body, and, indeed, wherever water 

 is violently agitated, flashes of light become 

 visible. The cause of this phenomenon de- 

 pends probably on the decomposing fibers of 

 dead mollusca, which are diffused in the 

 greatest abundance throughout the water. 

 If this luminous water be filtered through 

 finely woven cloths the fibers and membranes 

 appear like separate luminous points. 

 When we bathed at Cumana, in the Gulf of 

 Cariaco, and walked naked on the solitary 

 beach in the beautiful evening air, parts of 

 our bodies remained luminous from the 

 bright fibers and organic membranes which 

 adhered to the skin, nor did they lose this 

 light for some minutes. If we consider the 

 enormous quantity of mollusca which ani- 

 mate all tropical seas, we can hardly won- 

 der that sea-water should be luminous, even 

 where no fibers can be visibly separated from 

 it. HUMBOLDT Views of Nature, p. 249. 

 (Bell, 1896.) 



2590. PHOSPHORUS, DELUSION OF 



Chemistry of Brain Action Little Known. 

 Chemical action must of course accom- 

 pany brain activity. But little definite is 

 known of its exact nature. Cholesterin and 



creatin are both excrementitious products, 

 and are both found in the brain. The sub- 

 ject belongs to chemistry rather than to psy- 

 chology, and I only mention it here for the 

 sake of saying a word about a wide-spread 

 popular error about brain activity and phos- 

 phorus. " Ohne Phosphor kein Gedanke 

 [no thought without phosphorus] " was a 

 noted war-cry of the " materialists " during 

 the excitement on that subject which filled 

 Germany in the '60s. The brain, like every 

 other organ of the body, contains phos- 

 phorus and a score of other chemicals be- 

 sides. Why the phosphorus should be 

 picked out as its essence, no one knows. 

 It would be equally true to say " Ohne Was- 

 ser kein Gedanke [no thought without wa- 

 ter]," or " Ohne Kochsalz kein Gedanke [no 

 thought without salt] "; for thought would 

 stop as quickly if the brain should dry up 

 or lose its NaCl as if it lost its phosphorus. 

 JAMES Psychology, vol. i, ch. 3, p. 101. 

 (H. H. & Co., 1899.) 



2591 . PHOTOGRAPHY AS AN AID TO 

 ASTRONOMY A Photographic Survey of the 

 Heavens. Perhaps the most marvelous of 

 all achievements of photography is in the 

 field of astronomy. Every increase in the 

 size and power of the telescope has revealed 

 to us ever more and more stars in every 

 part of the heavens ; but by the aid of pho- 

 tography stars are shown which no telescope 

 that has been or that probably ever will be 

 constructed, can render visible to the human 

 eye. For by exposing the photographic plate 

 in the focus of the object-glass for some 

 hours almost infinitely faint stars impress 

 their image, and the modern photographic 

 star-maps show us a surface densely packed 

 with white points that seem almost as 

 countless as the sands of the seashore. 

 . . . A photographic survey of the heav- 

 ens is now in progress on one uniform 

 system, which when completed will form a 

 standard for future astronomers, and thus 

 give to our successors some definite knowl- 

 edge of the structure and perhaps of the 

 extent of the stellar universe. WALLACE 

 The Wonderful Century, ch. 5, p. 32. (D. 

 M. & Co., 1899.) 



2592. PHOTOGRAPHY, CUMULATIVE 

 EFFECT OF Extending Time of Exposure 

 Compensates for Feebleness of Light No 

 Cumulative Power in the Eye Vision the 

 Recognition of a Series of Photographs. 

 Seeing may be described, not wholly inaptly, 

 as the recognition of a series of brief suc- 

 cessive photographs taken by the optic lens 

 on the retina; but the important difference 

 between seeing and photographing, which 

 we now ask attention to, is this: When the 

 eye looks at a faint object, such as the 

 spectrum of a star, or at the still fainter 

 nebula, this, as we know, appears no bright- 

 er at the end of half an hour than at the 

 end of the first half-second. In other words, 

 after a brief fraction of a second, the visual 

 effect does not sensibly accumulate. But in 



