Painting 

 Parsimony 



SCIENTIFIC SIDE-LIGHTS 



508 



which have been preserved give an idea 

 what the paintings of Zeuxis and Apelles 

 may have been. The tourist visiting for the 

 first time the museum of Naples comes with 

 a shock of surprise in face of Alexander of 

 Athens' picture of the goddesses at play, 

 the boldly drawn frescos of scenes from the 

 " Iliad," and the groups of dancers elegant 

 in drawing and coloring. Most of these pic- 

 tures from Herculaneum and Pompeii were 

 done by mere house decorators, but these 

 tenth-rate Greek painters had the traditions 

 of the great classic school, and they show 

 plainly that from the same source we also 

 have inherited the art of design. TYLOR 

 Anthropology, ch. 12, p. 303. (A., 1899.) 



2500. PAIRS, STRANGELY ASSORT- 

 ED Bright Star with Dark Companion Fitful 

 and Intermittent Light. " Eclipse-stars " 

 are actually found in the heavens. The best 

 and longest-known member of the group is 

 Algol in the head of Medusa, the " Demon- 

 star " of the Arabs. This remarkable object, 

 normally of the second magnitude, loses and 

 regains three-fifths of its light once in 68. S 

 hours, the change being completed in about 

 ten hours. Its definite and limited nature 

 and punctual recurrence suggested to Good- 

 ricke of York, by whom the periodicity of 

 the star was discovered in 1783, the inter- 

 position of a large, dark satellite. But the 

 conditions involved by the explanation were 

 first seriously investigated by Pickering in 

 1880. He found that the phenomena could 

 be satisfactorily accounted for by supposing 

 an obscure body 0.764 of the bright star's 

 diameter to revolve round it in- a period 

 identical with that of its observed vari- 

 ation. This theoretical forecast was veri- 

 fied with singular exactitude at Potsdam in 

 1889. CLERKE History of Astronomy, pt. ii, 

 ch. 12, p. 469. (Bl., 1893.) 



2501. PARABLE A NECESSITY 



Truth Veiled, Not Dismembered. Edward 

 Irving [says] : " We must speak in parables, 

 or we must present a wry and deceptive 

 form of truth, of which choice the first is 

 to be preferred, and our Lord adopted it. Be- 

 cause parable is truth veiled, not truth dis- 

 membered; and as the eye of the under- 

 standing grows more piercing, the veil is 

 seen through, and the truth stands revealed/' 

 Nature is the great parable, and the truths 

 which she holds within her are veiled, but 

 not dismembered. The pretended separation 

 between that which lies within Nature and 

 that which lies beyond Nature is a dismem- 

 berment of the truth. Let both those who 

 find it difficult to believe in anything which 

 is " above " the natural, and those who in- 

 sist on that belief, first determine how far 

 the natural extends. Perhaps in going round 

 these marches they will find themselves 

 meeting upon common ground. For, indeed, 

 long before we have searched out all that the 

 natural includes, there will remain little in 

 the so-called supernatural which can seem 

 hard of acceptance or belief nothing which 



is not rather essential to our understanding 

 of this otherwise " unintelligible world." 

 ARGYLL Reign of Law, ch. 1, p. 32. (Burt.) 



2502. PARADOX OF NATURE Racier 



Preserved under Lava-stream. A remark- 

 able discovery was made on Etna in 1828 of 

 a great mass of ice, preserved for many 

 years, perhaps for centuries, from melting, 

 by the singular accident of a current of 

 red-hot lava having flowed over it. The fol- 

 lowing are the facts in attestation of a phe- 

 nomenon which must at first sight appear of 

 so paradoxical a character. The extraordi- 

 nary heat experienced in the south of Eu- 

 rope during the summer and autumn of 1828 

 caused the supplies of snow and ice which 

 had been preserved in the spring of that 

 year for the use of Catania ... to fail 

 entirely. . . . The magistrates of Catania 

 applied to Signer M. Gemmellaro, in the 

 hope that his local knowledge of Etna might 

 enable him to point out some crevice or 

 natural grotto on the mountain where drift- 

 snow was still preserved. Nor were they 

 disappointed; for he had long suspected 

 that a small mass of perennial ice at the 

 foot of the highest cone was part of a large 

 and continuous glacier covered by a lava 

 current. Having procured a large body of 

 workmen, he quarried into this ice, and 

 proved the superposition of the lava for 

 several hundred yards, so as completely to 

 satisfy himself that nothing but the sub- 

 sequent flowing of the lava over the ice 

 could account for the position of the glacier. 

 . . . We may suppose that at the com- 

 mencement of the eruption a deep mass of 

 drift-snow had been covered by volcanic 

 sand showered down upon it before the de- 

 scent of the lava. A dense stratum of this 

 fine dust mixed with scoriae is well known 

 to be an extremely bad conductor of heat; 

 and the shepherds in the higher regions of 

 Etna are accustomed to provide water for 

 their flocks during summer, by strewing a 

 layer of volcanic sand a few inches thick 

 over the snow, which effectually prevents 

 the heat of the sun from penetrating. Sup- 

 pose the mass of snow to have been pre- 

 served from liquefaction until the lower 

 part of the lava had consolidated, we may 

 then readily conceive that a glacier thus 

 protected, at the height of ten thousand 

 feet above the level of the sea, would en- 

 dure as long as the snows of Mont Blanc. 

 LYELL Geology, ch. 25, p. 412. (A., 1854.) 



2503. PARALLAX OF STARS Diffi- 

 culties that Beset the Problem Patience 

 and Exactness of Science. In the whole 

 of sidereal astronomy there is, perhaps, 

 nothing more difficult to determine than 

 the parallax of a star. To think that 

 among all the stars in the sky there is not 

 one which shows a parallax of one second 

 that is to say, an annual motion of two 

 seconds! Now, two seconds is. a millimeter 

 seen at a hundred meters, it is a hair of 

 a tenth of a millimeter seen at 10 meters 



