361 



SCIENTIFIC SIDE-LIGHTS 



Invention 

 Invisible 



much the most striking feature in the psy- 

 chology of this animal [a brown capuchin 

 monkey], and the one which is least like 

 anything met with in other animals, was 

 the tireless spirit of investigation. The 

 hours and hours of patient industry which 

 this poor monkey has spent in ascertain- 

 ing all that his monkey intelligence could of 

 the sundry unfamiliar objects that fell into 

 his hands might well read a lesson in care- 

 fulness to many a hasty observer. And the 

 keen satisfaction which he displayed when 

 he had succeeded in making any little dis- 

 covery, such as that of the mechanical prin- 

 ciple of the screw, repeating the results of 

 his newly earned knowledge over and over 

 again, till one could not but marvel at the in- 

 tent abstraction of the " dumb brute " this 

 was so different from anything to be met 

 with in any other animal* that I confess I 

 should not have believed what I saw unless 

 I had repeatedly seen it with my own eyes. 

 As my sister once observed while we were 

 watching him conducting some of his re- 

 searches, in oblivion to his food and all his 

 other surroundings, " When a monkey be- 

 haves like this it is no wonder that man is 

 a scientific animal!" ROMANES Animal In- 

 telligence, ch. 17, p. 497. (A., 1899.) 



1762. INVESTIGATION VS. DOGMA 



The Scientific Spirit. The history of 

 science teaches us the difficulties that have 

 opposed the progress of this active spirit of 

 inquiry. Inaccurate and imperfect obser- 

 vations have led, by false inductions, to the 

 great number of physical views that have 

 been perpetuated as popular prejudices 

 among all classes of society. Thus by the 

 side of a solid and scientific knowledge of 

 natural phenomena there has been preserved 

 a system of the pretended results of obser- 

 vation, which is so much the more difficult 

 to shake, as it denies the validity of the 

 facts by which it may be refuted. This 

 empiricism, the melancholy heritage trans- 

 mitted to us from former times, invariably 

 contends for the truth of its axioms with the 

 arrogance of a narrow-minded spirit. Phys- 

 ical philosophy, on the other hand, when 

 based upon science, doubts because it seeks 

 to ^investigate, distinguishes between that 

 which is certain and that which is merely 

 probable, and strives incessantly to perfect 

 theory by extending the circle of observa- 

 tion. HUMBOLDT Cosmos, vol. i, int., p. 38. 

 (H., 1897.) 



1 763. INVESTIGATORS OFTEN BAD 

 LECTURERS Advanced Thinker Sees Things 

 in Masses Anecdote of Laplace. An ad- 

 vanced thinker sees the relations of his 

 topics in such masses and so instantaneously 

 that when he comes to explain to younger 

 minds it is often hard to say which grows 

 the more perplexed, he or the pupil. In 

 every university there are admirable inves- 

 tigators who are notoriously bad lecturers. 

 The reason is that they never spontaneously 

 *ee the subject in the minute articulate way 



in which the student needs to have it offered 

 to his slow reception. They grope for the 

 links, but the links do not come. Bowditch, 

 who translated and annotated Laplace's 

 " Me"canique Celeste," said that whenever 

 his author prefaced a proposition by the 

 words " it is evident," he knew that many 

 hours of hard study lay before him. JAMES 

 Psychology, vol. ii, ch. 22, p. 369. (H. H. & 

 Co., 1899.) 



1764. INVIGORATION OF NEGA- 

 TIVE CHARACTER Overcoming, Not Re- 

 moval of Difficulties Self-reliance To Be 

 Fostered. With a character of [the nega- 

 tive] type, the object of the judicious edu- 

 cator will be to invigorate the whole nature, 

 corporeal as well as physical; to find out 

 what worthy objects of pursuit have the 

 most attraction for his pupil, and to aid and 

 encourage his steady pursuit of them, not 

 by removing difficulties from his path, but 

 by helping him to surmount them, and in 

 this manner to foster habits of self-reliance, 

 which, when once formed, whether in regard 

 to manly exercises or to the work of the 

 intellect, may be looked to as available for 

 the moral direction of the conduct. CAR- 

 PENTER Mental Physiology, bk. i, ch. 9, p. 

 428. (A., 1900.) 



1765. INVISIBLE, THE, MADE VISI- 

 BLE Ultraviolet Waves Revealed by Fluores- 

 cence. As a general rule, bodies either 

 transmit light or absorb it; but there is a 

 third case in which the light falling upon 

 the body is neither transmitted nor ab- 

 sorbed, but converted into light of another 

 kind. Professor Stokes, the occupant of the 

 chair of Newton in the University of Cam- 

 bridge, has demonstrated this change of one 

 kind of light into another, and has pushed 

 his experiments so far as to render the in- 

 visible rays visible. A large number of sub- 

 stances examined by Stokes, when excited 

 by the invisible ultraviolet waves, have been 

 proved to emit light. You know the rate of 

 vibration corresponding to the extreme vio- 

 let of the spectrum; you are aware that to 

 produce the impression of this color, the 

 retina is struck 789 millions of millions of 

 times in a second. At this point, the retina 

 ceases to be useful as an organ of vision, for 

 tho struck by waves of more rapid recur- 

 rence, they are incompetent to awaken the 

 sensation of light. ' But when such non- 

 visual waves are caused to impinge upon the 

 molecules of certain substances on those of 

 sulfate of quinin, for example they com- 

 pel those molecules, or their constituent 

 atoms, to vibrate; and the peculiarity is, 

 that the vibrations thus set up are of slower 

 period than those of the exciting waves. 

 By this lowering of the rate of vibration 

 through the intermediation of the sulfate of 

 quinin, the invisible rays are brought 

 within the range of vision. . . . Cast- 

 ing by means of a prism a spectrum . . . 

 upon a sheet of paper which has been wetted 

 with a saturated solution of the sulfate of 



