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THE POPULAR SCIENCE MONTHLY. 



" Does any one believe seriously that a can- 

 non-ball can be shot from the earth to the 

 moon ? But what harm is there ill letting 

 a child entertain a fancy of the kind for a 

 few hours ? He amuses himself with it, 

 and, while he is amused, he learns, without 

 conscious effort, that the moon revolves 

 around the earth, and the earth around the 

 sun, aud that there are forces of gravitation 

 and universal attraction, etc. . . . The false 

 idea does no harm, for nothing is built upon 

 it. ... I venture to say that it is advan- 

 tageous to inspire children with the love of 

 hazardous adventures, and the taste for the 

 unknown that they find in all the romances 

 of Jules Verne. They will encounter real 

 difficulties soon enough to be discouraged 

 from them earlier than they need to be. 

 Not to see the difficulties is sometimes a 

 good way to triumph over them. We have 

 all grown timid and hesitating, and it is not 

 a bad thing for us to be roused up to ardor 

 in chimerical enterprises, in which the power 

 of science is exhibited to us in the service 

 of an energetic will. It is, perhaps, on this 

 account, as much as for the amusement they 

 give us, that we avow a strong liking for 

 all of M. Verne's works. We might, if it 

 were worth while, defend M. Verne on other 

 considerations. When an idea enters the 

 mind of a child, what matter is it how it 

 gets there ? Whether it be in a romance, or 

 in a lesson, or in a text-book, or in a familiar 

 conversation, makes but little difference, so 

 the result is acquired. To tell a fourteen- 

 year-old boy that the diamond is crystallized 

 carbon, and that fruitless efforts have been 

 made to produce it artificially, is all very 

 well, but will he remember it? Are these 

 abstract facts interesting enough to stay? 

 Possibly; but the contrary is probable. 

 When you interest a child by relating to 

 him the adventures of Cyprian, as he puts 

 earth and charcoal into a crucible, and tries 

 to crystallize it into a diamond, the scien- 

 tific fact will not be forgotten ; and some 

 day Cyprian will retire into the background, 

 while the physical fact will be a permanent 

 acquisition, which he will owe to this new 

 mnemonic agency. It is more than mne- 

 monics. While M. Verne entertains us 

 with adventures, and fastens scientific facts 

 upon us, he also gives us a taste for sci- 

 ence. With him it is a goodly personage, 



smiling, affable, pleasant, greeting all who 

 come." 



Crickets and u Hair-Snakes." The so- 

 called horse - hair snake, as is known to 

 naturalists, is a parasite of the cricket, 

 which only becomes active under water. 

 Dr. H. C. McCook recently read a statement 

 before the Academy of Natural Sciences of 

 Philadelphia which indicates that the crick- 

 ets are aware of the peculiarity of their para- 

 sites, and take advantage of it to get rid of 

 them. A lady having moved into a house 

 which was a harbor for crickets, was troub- 

 led by frequently finding the hair-snakes 

 in her water-pails, a short time after the 

 water had been brought into the house. She 

 sat down to watch how they came there. In 

 a short time she saw " a particularly pleth- 

 oric cricket " mount upon the edge of the 

 pail, and, after some uneasy movements, 

 bring the tip of the abdomen just beneath 

 the water, and, with a few violent throes, 

 expel a black mass, which fell slowly through 

 the water, and, before it reached the bot- 

 tom, resolved itself into one of the worms. 

 The cricket seemed much exhausted by the 

 operation. 



Toxic Effects of Smoking. Dr. Zulinski, 

 of Warsaw, has made some experiments 

 upon the effects of tobacco-smoke, which 

 he determined to be a distinct poison, even 

 in small doses. Its action on men is very 

 slight when it is not inhaled in large quan- 

 tities, but it soon becomes powerful in those 

 who contract the habit of " swallowing the 

 smoke." The toxical property is not due 

 exclusively to the nicotine, but the smoke, 

 even when disengaged from nicotine, con- 

 tains a second toxical principle, called so- 

 lanine, besides carbonic oxide and hydro- 

 cyanic acid. The effects produced by smok- 

 ing depend upon the nature of the tobacco 

 and the way in which it is smoked. The 

 cigar-smoker absorbs more poison than the 

 cigarette-smoker, and he than the person 

 who smokes a pipe ; while the one who uses 

 a medium, by which the smoke is conducted 

 through water, reduces the deleterious effects 

 to a minimum. As a rule, the light-colored 

 tobaccos are supposed to be the mildest, but 

 they are sometimes artificially uncolored by 

 chemicals, the presence of which is danger- 



