FRAGMENTS OF SCIENCE. 



505 



lish. If the word "handful" had 

 parted with its essential meaning as 

 completely as say the word " troop " 

 has, for all but etymologists, there 

 would be no kind of incongruity in 

 its employment for any small num- 

 ber or quantity whatsoever. 



The scientific view of language, 

 then, is that it represents the effort 

 of mankind to use audible symbols 

 for the expression of thought; that 

 it follows the development of man's 

 activity and enlarges with his en- 

 larging knowledge, and comprehen- 

 sion of things; that while its ob- 

 ject is essentially a practical one it 

 gathers beauty with use and age, 

 and begins to react on the minds of 

 its makers; that its makers are the 

 people, not the grammarians, these 

 being merely its policemen, who, 

 useful in general, are sometimes too 

 oiEcious; that great writers are the 



architects who felicitously .arrange 

 materials which the people have 

 gathered and shaped, placing the 

 best of such materials where they 

 can be seen to best advantage ; final- 

 ly, that the language of each nation 

 is its most precious possession, the 

 record of its civilization, and the 

 repositoiy of all that is best in its 

 moral and intellectual life, and that 

 it is therefore the duty of all who 

 make any pretensions to liberal 

 training to watch over their herit- 

 age and, while allowing all reason- 

 able scope for further development, 

 to guard it by all means in their 

 power against degradation and pol- 

 lution. A great people will have a 

 great language : when a language 

 shows signs of weakness or declen- 

 sion, there is reason to fear for the 

 civilization of which it is the ex- 

 pression. 



g^ragiujewts crt Jijcijetucje. 



" Dark Lightning." — The attention 

 of meteorologists and photographers has 

 been engaged to a considerable extent, 

 within a few months past, with the ap- 

 pearance on photographs of lightning of 

 what seemed to be dark flashes as well 

 as bright ones. In the effort to account 

 satisfactorily for the phenomenon it has 

 been referred to photographic reversal, 

 due to extreme brilliancy; to a predomi- 

 nance of infra-red radiations; to the 

 existence of flashes deficient in actinic 

 rays; to changes in the density of the 

 air occasioned by the spark, when a 

 dark line with a light line within it is 

 shown if the air is compressed, and a 

 light line inclosing a dark one if it is 

 rarefied; and to some qualities of the 

 photographic plate. The first real light 

 was thrown on the subject by some ex- 

 periments described by Mr. A. W. Clay- 

 den, who, having photographed some 

 electric sparks of different intensities, 

 before developing the plates exposed 

 them to the diffused light of a gas. flame. 

 The brilliant sparks then yielded images 



which might either be called normal 

 with a reversed margin, or reversed with 

 a normal core, while the fainter images 

 were completely reversed — or, in other 

 words, came out darker than the back- 

 ground. The " fogging " of the picture, 

 to produce this reversal, must be done 

 after the image of the flash is impressed; 

 for if it is done before, the image ap- 

 pears lighter than the background. This 

 effect, which is called the " Clayden ef- 

 fect," is accepted as a satisfactory expla- 

 nation of the phenomenon by two of the 

 authors who have most studied it — Dr. 

 W. J. S. Lockyer and Prof. R. W. Wood, 

 of the University of Wisconsin. Professor 

 Wood, on repeating Mr. Clayden's ex- 

 periment, obtained dark flashes without 

 any difficulty, but as they failed to ap- 

 pear when the light of an incandescent 

 lamp was substituted for the electric 

 spark, he concludes that there is some- 

 thing in the spark essential to the re- 

 versal. Dr. Lockyer summarizes his con- 

 clusion by saying that dark-lightning 

 flashes " do not exist in Nature, but 



