Accumulation 

 Action 



SCIENTIFIC SIDE-LIGHTS 



or more other stimuli (equally ineffectual 

 by themselves alone) bring the discharge 

 about. The natural way to consider this 

 is as a summation of tensions which at last 

 overcome a resistance. The first of them 

 produce a " latent excitement," or a 

 " heightened irritability " the phrase is 

 immaterial so far as practical consequences 

 go; the last is the straw which breaks the 

 camel's back. JAMES Psychology, vol. i, ch. 

 3, p. 82. (H. II. & Co., 1899.) 



16. ACCUMULATION OF SMALL IM- 

 PULSES Great Results. Extraordinary 

 effects are produced by the accumulation of 

 small impulses. Galileo set a heavy pen- 

 dulum in motion by the well-timed puffs of 

 his breath. Ellicot set one clock going by 

 the ticks of another, even when the two 

 clocks were separated by a wall. TYN- 

 DALL Fragments of Science, vol. i, ch. 22, 

 p. 444. (A., 1900.) 



17. ACCURACY OF ANCIENT BUILD- 

 ERS Orientation of Great Pyramid Exact- 

 ness Not Attainable by Compass. It has 

 been frequently maintained that the orien- 

 tation of the great pyramid is such as to 

 indicate, with reasonable probability, that 

 the compass-needle was used in establishing 

 the positions of its faces. 



The difficulty with this supposition is 

 that the pyramid is, in fact, placed with 

 too great accuracy for the work to be done 

 even by the best modern compass. Its sides 

 face astronomically the north, south, east 

 and west; not to the cardinal points of the 

 compass, but to the azimuthal direction of 

 the earth's axis and to a line at right angles 

 thereto. The compass, however, is subject 

 to variations, due to regular daily, monthly, 

 yearly, and centennial changes in the earth's 

 magnetic field, which controls it. Hence, 

 the task of figuring backward the probable 

 position of the needle at the time of the 

 building of the pyramid a period which is 

 in doubt might well cause despair in the 

 most skilful investigator of terrestrial 

 magnetism ; for, in the least interval which 

 has elapsed, the needle has probably swung 

 over large angles from the true north, back 

 and forth many times. But, granting such 

 a possibility, still it may be safely ques- 

 tioned whether the most accomplished sur- 

 veyor or topographical engineer of to-day 

 could run the lines of the pyramid faces, by 

 the aid of the best modern compass, with 

 no greater error than 19' 58", which the 

 French Academy, in 1799, determined to be 

 the entire amount of variation of these 

 faces from the true astronomical direction. 

 PARK BENJAMIN Intellectual Rise in Elec- 

 tricity, ch. 3. p. 57. (J. W., 1898.) 



18. ACCURACY OF DETAIL The 



Charm Alike of Science. Literature, and 

 Art. In the sphere of natural investiga- 

 tion, as in poetry and painting, the delinea- 

 tion of that which appeals most strongly to 

 the imagination, derives its collective inter- 



est from the vivid truthfulness with which 

 the individual features are portrayed. 

 HUMBOLDT Cosmos, vol. i, int., p. 34. (H., 

 1897.) 



19. ACCURACY OF MODERN ASTRO- 

 NOMICAL INSTRUMENTS All the Light 

 Gathered by a Two-foot Lens Concentrated 

 on a Pin-point. The revolving dome above, 

 the great tube beneath, its massive piers, 

 and all its accessories are only means to 

 carry and direct the great lens at the fur- 

 ther end [of the equatorial telescope at 

 Washington], which acts the part of the 

 lens in our own eye, and forms the image of 

 the thing to be looked at. Galileo's original 

 lens was a single piece of glass, rather 

 smaller than that of our common spec- 

 tacles; but the lens here is composed of 

 two pieces, each twenty-six inches in diam- 

 eter, and collects as much light as a human 

 eye would do if over two feet across. But 

 this is useless if the lens is not shaped with 

 such precision as to send every ray to its 

 proper place at the eye-piece, nearly thirty- 

 five feet away; and, in fact, the shape given 

 its surface by the skilful hands of the 

 Messrs. Clark, who made it, is so exqui- 

 sitely exact that all the light of a star gath- 

 ered by this great surface is packed at the 

 distant focus into a circle very much 

 smaller than that made by the dot on this 

 i, and the same statement may be made of 

 the great Lick glass, which is three feet in 

 diameter an accuracy we might call in- 

 credible were it not certain. It is with in- 

 struments of such accuracy that astronomy 

 now works. LANGLEY The New Astronomy, 

 ch. 5, p. 122. (H. M. & Co.) 



20. ACTION A CELESTIAL LAW 



Every Star in Motion. So far as observa- 

 tion has extended very few stars in the 

 heavens have unchanging apparent posi- 

 tions. It is highly probable that in reality 

 every star is in motion. PROCTOR Expanse 

 of Heaven, p. 282. (L. G. & Co., 1897.) 



21. ACTION AND REACTION Increase 



of Magnetic Power Progress of Scientific 

 Discovery. The aspects of Nature provoke 

 in man the spirit of inquiry. As the eye is 

 formed to see, and the ear to hear, so the 

 human mind is formed to explore and un- 

 derstand the basis and relationship of 

 natural phenomena. A modern discovery 

 illustrates the manner in which our present 

 mastery over Nature has been obtained. We 

 start with a magnet of infinitesimal power, 

 which gives rise to electric currents of in- 

 finitesimal strength. These react upon the 

 magnet, exalt its attractive and repulsive 

 forces, thus enabling it to produce stronger 

 currents, which again react upon and en- 

 hance the power of their source. Thus we 

 rise from an origin too feeble to produce 

 the slightest spark or gleam, to an energy 

 competent to produce the solar brilliancy of 

 the electric light. In a similarly small way 

 the human mind began its operations among 

 the powers of Nature, winning first a little 



