515 



SCIENTIFIC SIDE-LIGHTS 



'atience 

 erception 



whole of the sixteenth centuries. HUM- 

 BOLDT Cosmos, vol. ii, pt. ii, p. 263. (H., 

 1897.) 



2534. PENETRATION OF LIGHT 

 THROUGH WATER No Sunlight in Ocean 

 Depths. The entire absence of solar light, 

 which constitutes another most important 

 peculiarity in the conditions of deep-sea life, 

 would seem at first sight to be an absolute 

 bar to its maintenance. Experimental evi- 

 dence has not yet, I believe, been obtained 

 of the direct penetration of the solar rays 

 to more than 100 fathoms; but as I dredged 

 slow-growing red calcareous algae (true cor- 

 allines) in the Mediterranean at a depth of 

 150 fathoms (at or below which Edward 

 Forbes also would seem to have met with 

 them), the actinic, if not the luminous, rays 

 must probably penetrate to that range. Be- 

 low what Edward Forbes termed the coral- 

 line zone it would seem impossible that any 

 other type of vegetable life can be sustained 

 than such as has the capacity of the fungi 

 for growing in the dark, living, like them, 

 upon material supplied by the decomposition 

 of organic compounds. Such lowly plants 

 have been found by Professor P. M. Duncan 

 in corals dredged from more than 1,000 

 fathoms' depth. CARPENTER Nature and 

 Man, lect. 11, p. 345. (A., 1889.) 



2535. PENTATEUCH IN HARMONY 

 WITH ARCHEOLOGY Bronze before Iron 

 Progress from the Ductile to the Stub- 

 lorn Metal. The forms of early weapons 

 indicate that those of iron were copied from 

 bronze, not those of bronze from iron. Hesi- 

 od's poems, as well as those of Homer, show 

 that nearly three thousand years ago the 

 value of iron was known and appreciated. 

 It is true that, as we read in Dr. Smith's 

 " Dictionary of Greek and Roman Antiqui- 

 ties," bronze " is represented in the " Iliad " 

 and " Odyssey " as the common material of 

 arms, instruments, and vessels of various 

 sorts; the latter (iron) is mentioned much 

 more rarely." While, however, the above 

 statement is strictly correct, we must re- 

 member that among the Greeks the word 

 iron (<riSr}po) was used, even in the time 

 of Homer, as synonymous with a sword, and 

 that steel also appears to have been known 

 to them under the name of afia/maf, and per- 

 haps also of Kvavo, as early as the time 

 of Hesiod. We may, therefore, consider that 

 the Trojan war took place during the period 

 of transition from the Bronze to the Iron 

 Age. 



In the Pentateuch, including Deuteron- 

 omy, bronze, or, as it is unfortunately trans- 

 lated, " brass," is mentioned thirty-eight 

 times, and iron only four times. AVEBURY 

 Prehistoric Times, ch. 1, p. 5. (A., 1900.) 



2536. "PEPPER-POT" OF TROPICAL 

 AMERICA An Invention of Woman. The In- 

 dian women of Guiana are excellent purvey- 

 ors. They have but one way of cooking meat 

 or fish, and that is by boiling it down into 

 a sort of thick soup, with peppers and cas- 



sareep, or the juice of strained cassava 

 boiled down to a sirup. The cassareep re- 

 duces all meat to one common flavor its 

 own and has antiseptic qualities which 

 keep meat boiled in it good for a long time. 

 The result is the far-famed pepper-pot, 

 which all settlers in the West Indies have 

 learned to make and to like. MASON Wom- 

 an's Share in Primitive Culture, ch. 2, p. 38. 

 (A., 1894.) 



2537. PERCEPTION INCREASED BY 

 HABITUAL ATTENTION Deaf-and-dumb 

 Lip-reading. It has long been known that 

 individuals among the deaf and dumb have 

 acquired the power of " lip-reading " ; that 

 is, of so interpreting the visible movements 

 of the mouth and lips of a speaker as to 

 apprehend the words he utters, no less ac- 

 curately than if they were heard. And it 

 has been latterly proposed to make this a 

 matter of systematic instruction, so that 

 every deaf-mute should be enabled to under- 

 stand what is said, without the aid of the 

 "sign-language" or the "finger-alphabet." 

 It appears, however, that it is not every one 

 who is capable of acquiring this power, and 

 it is still questionable whether it can be 

 even generally attained by any amount of 

 practise. [It has been done on a consider- 

 able scale.] But that it should have been 

 even exceptionally acquired shows the ex- 

 traordinary improvability of the perceptive 

 faculty. CARPENTER Mental Physiology, bk. 

 i, ch. 5, p. 204. (A., 1900.) 



2538 . PERCEPTION, JUDGMENT, AND 

 PERSEVERANCE NEEDED FOR SUCCESS- 

 FUL SELECTION Accumulation of Almost 

 Imperceptible Differences. When a cross [in 

 breeding] has been made, the closest selection 

 is far more indispensable even than in ordi- 

 nary cases. If selection consisted merely in 

 separating some very distinct variety and 

 breeding from it, the principle would be so 

 obvious as hardly to be worth notice; but 

 its importance consists in the great effect pro- 

 duced by the accumulation in one direction, 

 during successive generations, of differences 

 absolutely inappreciable by an uneducated 

 eye differences which I for one have vainly 

 attempted to appreciate. Not one man in 

 a thousand has accuracy of eye and judg- 

 ment sufficient to become an eminent breed- 

 er. If gifted with these qualities, and he 

 studies his subject for years, and devotes 

 his lifetime to it with indomitable persever- 

 ance, he will succeed, and may make great 

 improvements; if he wants any of these 

 qualities, he will assuredly fail. Few would 

 readily believe in the natural capacity and 

 years of practise requisite to become even 

 a skilful pigeon-fancier. DARWIN Origin 

 of Species, ch. 1, p. 27. (Burt.) 



2539. PERCEPTION LARGELY PSY- 

 CHIC We See What We Know or Believe To 

 Be. The grass out of the window now looks 

 to me of the same green in the sun as in 

 the shade, and yet a painter would have to 



