Invisible 



Isolation 



SCIENTIFIC SIDE-LIGHTS 



quinin. and afterwards dried, an obvious 

 extension of the spectrum is revealed. We 

 have, in the first instance, a portion of the 

 violet rendered whiter and more brilliant; 

 but, besides this, we have the gleaming of 

 the color where, in the case of unprepared 

 paper, nothing is seen. Other substances 

 produce a similar effect. A substance, for 

 example, recently discovered by President 

 Morton, and named by him thallene, pro- 

 duces a very striking elongation of the spec- 

 trum, the new light generated being of pe- 

 culiar brilliancy. . . . [Stokes] called 

 this rendering visible of the ultraviolet rays 

 fluorescence. TYNDALL Lectures on Light, 

 lect. 4, p. 163. (A., 1898.) 



1766. IRON AMONG THE HEBREWS 



Discovery of Dim Antiquity. It has been 

 suggested that such iron as has been found 

 in Egypt, and referred to Pharaonic times, 

 may have been made and used by the He- 

 brews during their servitude, and that when 

 they left the country they carried their 

 knowledge with them. That they were fa- 

 miliar with the metal at the period of 

 Moses, and hence at about 1500 years B. C., 

 and possibly had known of it then for a long 

 time, is shown by the mention of Tubal 

 Cain, " an instructor of every artificer in 

 brass and iron," as a personage of great an- 

 tiquity, at the very beginning of the Pen- 

 tateuch. Their continuing knowledge of it, 

 over many centuries, is further shown by the 

 Biblical references to the bed of iron of Og, 

 the iron chariots of Javin, the miraculous 

 floating ax-head of Elisha, the question 

 " shall iron break the northern iron and the 

 steel " in the Jeremiad, and many other in- 

 stances, easily found. PARK BENJAMIN In- 

 tellectual Rise in Electricity, ch. 1, p. 28. 

 (J. W., 1898.) 



1767. IRRELIGION MAY RESULT 

 FROM DEGENERACY It must be re- 

 membered that even if it had been true that 

 some savages do exist with no conception 

 whatever of living beings higher than them- 

 selves, it would be no proof whatever that 

 such was the primeval condition of man. 

 The . . . most degraded savagery of the 

 present day is or may be the result of evo- 

 lution working upon highly unfavorable con- 

 ditions. . . . Degradation being a proc- 

 ess which has certainly operated, and is now 

 operating upon some races, and to some ex- 

 tent, it must always remain a question how 

 far this process may go in paralyzing the 

 activity of our higher powers, or in setting 

 them, as it were, to sleep. ARGYLL Unity of 

 "Nature, ch. 11, p. 281. (Burt.) 



1768. IRRIGATION, SYSTEM OF, 

 AMONG NORTH-AMERICAN INDIANS- 

 No aborigines, unaided by domestic animals, 

 have displayed so much patience and inge- 

 nuity in the storage and conducting of wa- 

 ter as the Indians of the arid region of the 

 United States. Throughout the jmblic 

 region, says Mr. Hodge, works of irriga- 

 tion abound in the valleys and on the moun- 



tain slopes, especially along the drainage 

 of the Gila and the Salado, in Southern 

 Arizona, where the inhabitants are engaged 

 in agriculture to a vast extent by this 

 means. The arable tract of the Salado com- 

 prises 450,000 acres, and the ancient in- 

 habitants controlled the watering of at least 

 250,000 acres. The outlines of one hundred 

 and fifty miles of ancient main irrigating 

 ditches may be readily traced, some of which 

 meander southward a distance of fourteen 

 miles. In one place the main canal was 

 found to be a ditch within a ditch, the bed 

 being seven feet deep. The lower section 

 was only four feet wide, but the sides broad- 

 ened in their ascent to a " bench " three feet 

 wide on each side of the canal. Remains of 

 balsas were recovered, showing that the 

 transportation of material was also carried 

 on. Remains of flood-gates were found by 

 Mr. Gushing, and great reservoirs for stor- 

 age of water, one example being 200 feet 

 long and 15 feet in depth. MASON Aborig- 

 inal American Mechanics (Memoirs of the 

 International Congress of Anthropology, p. 

 82). (Sch. P. C.) 



1769. IRRITATION OF SKIN BY 

 ALPINE SUNSHINE Power of Chemical 

 Rays. There would seem to be some specific 

 quality in the sun's rayg which produces the 

 irritation of the skin experienced in the 

 Alps. The solar heat may be compared, in 

 point of quantity, with that radiated from a 

 furnace; and the heat encountered by the 

 mountaineer on Alpine snows is certainly 

 less intense than that endured by workmen 

 in many of our technical operations. But 

 the terrestrial heat appears to lack the 

 quality which gives the solar rays their 

 power. The sun is incomparably richer in 

 what are called chemical rays than are our 

 fires, and to such rays the irritation may be 

 due. TYNDALL Hours of Exercise in the 

 Alps, ch. 15, p. 169. (A., 1898.) 



1770. ISLAND CREATED IN ONE 

 GENERATION There can be little doubt, 

 from the account given by Captain Beechey, 

 that Matilda Atoll in the Low Archipela- 

 go has been converted in the space of thirty- 

 four years from being, as described by the 

 crew of a wrecked whaling-vessel, a " reef 

 of rocks," into a lagoon-island fourteen 

 miles in length, with " one of its sides cov- 

 ered nearly the whole way with high trees." 

 The islets, also, on Keeling Atoll, it has been 

 shown, have increased in length, and since 

 the construction of an old chart several of 

 them have become united into one long 

 islet. DARWIN Coral Reefs, ch. 4, p. 101. 

 (A., 1900.) 



1771. ISLAND RISES AMONG 

 AZORES Wide-spread Earthquakes Distant 

 Echo of Eruption. The sudden appearance, 

 on the 30th of January, 1811, of the island 

 of Sabrina, in the group of the Azores, was 

 the precursor of the dreadful earthquakes 

 which, further westward, shook, from May, 

 1811, to June, 1813, almost uninterruptedly, 



