Extension 

 Extravagances 



SCIENTIFIC SIDE-LIGHTS 



struments of observation) increases the in- 

 tellectual and not unfrequently the physical 

 powers of man. More rapid than light, the 

 closed electric current conveys thought and 

 will to the remotest distance. Forces, whose 

 silent operation in elementary nature, and 

 in the delicate cells of organic tissues, still 

 escape our senses, will, when recognized, 

 employed, and awakened to higher activity, 

 at some future time enter within the sphere 

 of the endless chain of means which enable 

 man to subject to his control separate do- 

 mains of Nature, and to approximate to a 

 more animated recognition of the universe 

 as a whole. HUMBOLDT Cosmos, vol. ii, 

 pt. ii, p. 355. (H., 1897.) 



1160. EXTENSION OF SUGGESTION 



From Waves of Sound to Waves of Light 

 The Luminiferous Ether A Priori Judg- 

 ment of the Creator's Will. It was known 

 long ago that sound is conveyed in waves 

 or pulses through the air; and no sooner 

 was this truth well housed in the mind 

 than it was transformed into a theoretic 

 conception. It was supposed that light, like 

 sound, might also be the product of wave- 

 motion. But what, in this case, could be 

 the material forming the waves? For the 

 waves of sound we have the air of our at- 

 mosphere; but the stretch of imagination 

 which filled all space with a luminiferous 

 ether trembling with the waves of light was 

 so bold as to shock cautious minds. In one 

 of my latest conversations with Sir David 

 Brewster, he said to me that his chief ob- 

 jection to the undulatory theory of light 

 was that he could not think the Creator 

 guilty of so clumsy a contrivance as the fill- 

 ing of space with ether in order to produce 

 light. This, I may say, is very dangerous 

 ground, and the quarrel of science with Sir 

 David, on this point, as with many esti- 

 mable persons on other points, is, that they 

 profess to know too much about the mind 

 of the Creator. TYNDALL Lectures on 

 Light, lect. 2, p. 48. (A., 1898.) 



1161. EXTENSION OF THE SPEC- 

 TRUM The Invisible Outnumber the Visible 

 Rays. A layman would suppose that the 

 endeavors of physicists to lengthen out the 

 visible spectrum would cease with the very 

 considerable additions due to the direct 

 photography of rays ultraviolet and ultra- 

 red. But the lay mind knows little of the 

 persistence and address of the accomplished 

 physicist, and can only marvel at the mode 

 in which he summons fresh resources from 

 points of the compass at first seeming the 

 farthest removed from his task. 



Prof. S. P. Langley, Secretary of the Smith- 

 sonian Institution at Washington, has re- 

 fined the galvanometer into an appliance 

 which he styles the bolometer. Its delicate 

 wire, much thinner than a human hair, 

 through which an electric current constant- 

 ly passes, and sensitive to much less than 

 the ten-millionth of a degree centigrade, 

 is moved by minute steps through the in- 



visible areas of the solar spectrum; each 

 indication of temperature, automatically 

 photographed, comes out as a line which 

 varies in depth of tone with the intensity 

 of the thermal ray. When the device has 

 finished its journey the larger part of the 

 whole breadth of solar radiation rises to 

 view in all fifteen times as extensive as 

 the spectrum which Newton saw. ILES 

 Flame, Electricity, and the Camera, ch. 

 24, p. 346. (D. & McC., 1900.) 



1162. EXTERMINATION BY DIVER- 

 SION OF SUPPLIES Willows on Bank De- 

 stroy Watercress in Stream. A curious ex- 

 ample of the struggle between plants has 

 been communicated to me by Mr. John 

 Ennis, a resident in New Zealand. The 

 English watercress grows so luxuriantly 

 in that country as to completely choke up 

 the rivers, sometimes leading to disastrous 

 floods, and necessitating great outlay to 

 keep the stream open. But a natural rem- 

 edy has now been found in planting wil- 

 lows on the banks. The roots of these trees 

 penetrate the bed of the stream in every 

 direction, and the watercress, unable to ob- 

 tain the requisite amount of nourishment, 

 gradually disappears. WALLACE Darwin- 

 ism, ch. 2, p. 17. (Hum., 1889.) 



1 163. EXTERMINATION OF GAME BY 

 MODERN WEAPONS Survival of Hunting as 

 ran Amusement. The modern hunter has a 



vastly increased power of killing game, 

 from the use of firearms instead of the 

 bow and spear which came down from sav- 

 age times. The effect of bringing in guns 

 is seen among the native American buffalo- 

 hunters. They were always reckless in 

 destruction when they once came within 

 reach of the herds, but now with the help 

 of the white man and the use of his rifles 

 there is such slaughter that travelers have 

 found the ground and air for miles foul 

 with the carcasses of buffaloes, killed merely 

 for the hides and tongues. In the civilized 

 world, what with killing off game, and what 

 with the encroachment of agriculture on the 

 wild lands, both the supply and the need 

 of game for man's subsistence have much 

 lessened. But the hunter's life has been 

 from the earliest times man's school of en- 

 durance and courage, where success and 

 even trial gives pleasure in one of its in- 

 tensest forms. Thus it has come to be kept 

 up artificially where its practical use has 

 fallen away. In civilized countries it is 

 seen at its" best where it keeps closest to 

 barbaric fatigue and danger, like grouse- 

 shooting in Scotland, or boar-hunting in 

 Austria; but at its meanest, where it has 

 come down to shooting grain-fed pheasants 

 as tame as barn-door fowls. TYLOR An- 

 thropology, ch. 9, p. 210. (A., 1899.) 



1164. EXTERMINATION OF PLANT 

 BY PLANT (Matt, ariii, 7) If turf which 

 has long been mown and the case would 

 be the same with turf closely browsed by 

 quadrupeds be let to grow, the more vig- 



