399 



SCIENTIFIC SIDE-LIGHTS 



Light 

 Lightning 



and not " baseless as the fabric of a vision." 

 LANGLEY New Astronomy, ch. 2, p. 41. 

 (H. M. & Co., 1896.) 



1947. LIGHT, WAVES OF, ABOLISH 

 EACH OTHER- Motion of Light Differs from 

 That of Sound. On the assumption that 

 light was wave-motion, all his [Thomas 

 Young's] experiments on interference were 

 explained; on the assumption that light 

 was flying particles, nothing was explained. 

 In the time of Huyghens and Euler a me- 

 dium had been assumed for the transmission 

 of the waves of light; but Newton raised 

 the objection that, if light consisted of the 

 waves of such a medium, shadows could not 

 exist. The waves, he contended, would bend 

 round opaque bodies and produce the motion 

 of light behind them, as sound turns a cor* 

 ner or as waves of water wash round a rock. 

 It was proved that the bending-round re- 

 ferred to by Newton actually occurs, but 

 that the inflected waves abolish each other 

 by their mutual interference. Young also 

 discerned a fundamental difference Jbetween 

 the waves of light and those of sound. 

 Could you see the air through which sound- 

 waves are passing, you would observe every 

 individual particle of air oscillating to and 

 fro in the direction of propagation. Could 

 you see the luminiferous ether, you would 

 also find every individual particle making a 

 small excursion to and fro; but here the 

 motion . . . would be across the line 

 of propagation. The vibrations of the air 

 are longitudinal, those of the ether trans- 

 versal. TYNDALL Lectures en Light, lect. 

 2, p. 59. (A., 1898.) 



1948. LIGHT WHERE SUITS RAYS 

 NEVER COME Rows of Lights on Sides of 

 Deep-sea Fish The Scopelus. We can dis- 

 tinguish two kinds of phosphorescent organs 

 in the deep-sea fish. There are the curious 

 eye-like or ocellar organs situated usually in 

 one or more rows down the sides of the 

 fish's body, forming as it were a series of 

 miniature bull's-eye lanterns to illuminate 

 the surrounding sea, and various glandular 

 organs that may be situated at the extrem- 

 ity of the barbels or in broad patches behind 

 the eyes or in other prominent places on the 

 head and shoulders. Ocellar organs have 

 been known for many years to occur on the 

 sides of the interesting pelagic fish, Scopelus. 

 Most of the species of this genus live in the 

 open sea at moderate depths, coming to the 

 surface only at night, but other species are 

 found in almost every depth down to 2,000 

 fathoms of water. HICKSON Fauna of the 

 Deep Sea, ch. 4, p. 77. (A., 1894.) 



1949. LIGHTHOUSE OF THE MED- 

 ITERRANEAN " The Island Volcano of 

 Stromboli. Viewed at night-time, Strom- 

 boli presents a far more striking and singu- 

 lar spectacle. The mountain, owing to its 

 great elevation, is visible over an area hav- 

 ing a radius of more than 100 miles. When 

 watched from the deck of a vessel anywhere 

 within this area, a glow of red light [caused 



by the light of internal fires reflected from 

 the overhanging cloud of vapor] is seen to 

 make its appearance from time to time 

 above the summit of the mountain; this 

 glow of light may be observed to increase 

 gradually in intensity, and then as gradu- 

 ally to die away. After a short interval the 

 same appearances are repeated, and this 

 goes on till the increasing light of the dawn 

 causes the phenomenon io be no longer 

 visible. The resemblance presented by 

 Stromboli to a "flashing light" on a most 

 gigantic scale is very striking, and the 

 mountain has long been known as "the 

 lighthouse of the Mediterranean." JUDD 

 Volcanoes, ch. 2, p. 10. (A., 1899.) 



1950. LIGHTING, METHODS OF 



Torches Reach Down to Modern Days 

 Greek and Roman Lamps The Argand 

 Burner. Till this century we used torches 

 much as the ancient Romans did, but they 

 are now seldom to be seen, and by their dis- 

 use the picturesque side of life loses many 

 striking effects of torchlight glare and 

 shadow on banquet and procession the de- 

 light of painters and poets. Not half the 

 passers-by in old-fashioned streets now know 

 that the extinguishers on the iron railings 

 were to put out the links or torches carried 

 to light the company to their coaches. The 

 candle looks as tho it might have been in- 

 vented from the torch. The rushlight, made 

 of the pith of the rush dipped in melted fat, 

 was in common use in Pliny's time, as was 

 also the wax or tallow candle with its yarn 

 wick. The old classic lamp was a flattish 

 oval vessel with a nozle (i. e., nostril) at 

 one end for the wick to come out at. Simple 

 as this construction is, it has had a long 

 unchanged use. Museums have few Greek 

 and Roman objects more plentiful than such 

 earthenware lamps, nor more exquisite 

 specimens of metal-work than the bronze 

 ones; and to this day the traveler off the 

 main road in Spain or Italy is lighted to 

 his bedroom with a brass stand-lamp much 

 after the manner of the ancients, with its 

 pickwick hanging to it by a chain. The 

 lamp only came into its improved modern 

 make about a century ago, when Argand let 

 the air in from below, and put on the glass 

 chimney to set up a draft. TYLOB Anthro- 

 pology, ch. 11, p. 272. (A., 1899.) 



1951. LIGHTNING, PHENOMENA OF 



House Struck by Sleeper Strangely Pre- 

 served. Professor Henry . . . stated that 

 he had lately examined a house struck by 

 lightning, which exhibited some effects of an 

 interesting kind. The lightning struck the 

 top of the chimney, passed down the interior 

 of the flue to a point opposite a mass of iron 

 placed on the floor of the garret, where it 

 pierced the chimney; thence it passed ex- 

 plosively (breaking the plaster) into a bed- 

 room below, where it came in contact with 

 a copper bell-wire, and passed along this 

 horizontally and silently for about six feet; 

 thence it leaped explosively through the air 



