FOR GENERAL READERS. 



Vol. I. — No. 17. {New Series.) 



FRIDAY, APRIL 27th, il 



rWeekly, Price 3d. 

 L By Post. Sjd. 



Current Events 



Scientific Table Talk ... 



The Panama Canal Locks (iHus.) 



Foraminifera. — I. (illus.) 



The Cloudiness of the Sky and the 



Products of the Land 



General Notes ... 

 The Comet (illus.) 

 The Effect of Gas upon Paper 



A Wheel Puzzle (ito<j.) 



The Hypothesis of Adhemar... 

 Natural History : 



A Dwarf Armadillo — Chlamydo- 

 phorus truncatus (illus.) 



Mosquito Bites 



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 386 



387 



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390 

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393 

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395 

 396 



Fight between a Leopard and a Bear 397 



C ONTENTS . 



Miscellaneou'S Notes 



Scale Insects 



The Lick Observatory. — II 



Reviews ; 



The Testing of Materials of Con- 

 struction 

 Elementary Chemistry — Inorganic 



and Organic 

 Transactions of the Manchester 



Geological Society 



Journal of the Society of Tele- 

 graph Engineers and Elec- 

 tricians 

 Examiners and Candidates 

 Abstracts of Papers, Lectures, etc. : 

 Royal Institution 



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397 

 397 

 398 



399 



400 

 400 



Royal Society 



Geological Society 



Victoria Institute - 



Liverpool Geological Society ... 

 Agricultural Education and Dairy 



Instruction — I 



Correspondence : 



Milk as a Vehicle of Disease — 



The Lemmings of Norway 



Answers to Correspondents 



Recent Inventions 

 Technical Education ... 



Announcements 



Diary for Next Week 



Sales and Exchanges ... 



Notices 



FAGB 



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 408 



CURRENT EVENTS. 



Bicentenary of Newton's Principia. — In commem- 

 oration of the bicentenary of the publication of 

 Newton's Principia, Dr. Glaisher delivered an in- 

 teresting address last week at Cambridge. He pointed 

 out that from the moment Newton considered ^the pos- 

 sibility of comparing terrestrial gravity with the force that 

 held the moon in her orbit, he had formed the brilliant 

 conception that attraction was an inherent property of 

 every individual particle of matter. In this Newton 

 never wavered, and between this very definite and 

 accurate conception, and the vague notions about 

 gravitation that were current in his day, there was an 

 enormous difierence. In 1685 there was his remark- 

 able achievement of determining mathematically the 

 attraction of a spherical mass, which had so important 

 a bearing on the establishment of the theory of gravita- 

 tion. The actual composition of the " Principia " was 

 preceded by the attempt in 1666 to connect gravity with 

 the moon's motion, and a correspondence with Hooke 

 in 1679, when the elliptic orbit about the focus was de- 

 monstrated. In 1679 he was engaged upon other investiga- 

 tions, and laid aside the calculations he had then prepared. 

 Five years later he was led to take up the subject again, 

 but was then unable to find his previous calculations, and 

 so was obliged to work them out again. With the excep- 

 tion of some minor propositions, the whole of the Prin- 

 cipia was composed from very scanty materials in the 

 short period of eighteen months — the result of a single 

 continuous tftbrt. 



The great event that stands out conspicuously in this 

 memorable time is the determination of the attraction of 

 spheres, and this remarkable result was unexpected 

 by Newton himself. The effect of this sudden transition 



from approximation to exactitude stimulated his mind to 

 still greater efforts, and it was now in his power to apply 

 mathematical analysis with absolute precision to the 

 actual problems of astronomy. " Thus was it granted to 

 one man to be the first to forma conception of the true prin- 

 ciple that governed the universe, to give precise mean- 

 ing to his brilliant conception, and by the aid of a mathe- 

 matical weapon which he himself had forged to wrest 

 from his great principle its varied and subtle consequence?, 

 and even in the most difficult problem of all, the motion 

 of the moon, to outstrip the observations of his time." 



Mr. Matthew Arnold. — It is not for us to speak of 

 the dead poet and critic, but at least we may pay our 

 tribute to the man whose untiring efforts and acute think- 

 ing have done so much for the cause of primary and 

 secondary education. His critical inquiries abroad, made 

 in the capacity of Foreign Assistant Commissioner in 1859, 

 and as a Special Commissioner in 1865, were fruitful seed 

 in so fertile a mind, and the fruit they produced has led 

 to a wide-spread demand for improvement in middle-class 

 education — a demand which has silently and surely 

 undermined the methods formerly in vogue, and broken 

 down to some considerable extent the strange barriers of 

 limitation which divided the " Philistines " from the 

 " Barbarians" on the one hand, and the "Populace" on 

 the other. For thirty-five years he was an Inspector of 

 Elementary Schools, and he thus acquired a long and 

 varied experience which was of great value, and his re- 

 ports form a repository of wise suggestion whence may 

 be drawn plans for steady progress in the near and re- 

 mote future. At the same time the drudgery of such 

 work must have been very irksome, although he per- 

 formed it in a most exemplary manner, and it is to be 



