Advance 

 Aeronaut 



SCIENTIFIC SIDE-LIGHTS 



18 



der; and I do not think that Newton has a 

 surer claim to the discoveries that have 

 made his name immortal than Kirchhoff 

 has to the credit of gathering up the frag- 

 mentary knowledge of his time, of vastly 

 extending it, and of infusing into it the life 

 of great principles. TYNDALL Lectures on 

 Light, lect. 6, p. 206. (A., 1898.) 



86. ADVANCE OF LEARNING IN SEV- 

 ENTEENTH CENTURY A Galaxy of Dis- 

 coveries. A few names will suffice to give 

 an idea of the gigantic strides with which 

 the human mind advanced in the seven- 

 teenth century, especially in the develop- 

 ment of mathematical induction, under the 

 influence of its own subjective force rather 

 than from the incitement of outward cir- 

 cumstances. The laws which control the 

 fall of bodies and the motions of the planets 

 were now recognized. The pressure of the 

 atmosphere; the propagation of light, and 

 its refraction and polarization, were inves- 

 tigated. Mathematical physics were created, 

 and based on a firm foundation. The in- 

 vention of the infinitesimal calculus char- 

 acterizes the close of the century; and, 

 strengthened by its aid, human understand- 

 ing has been enabled, during the succeeding 

 century and a half, successfully to venture 

 on the solution of the problems presented by 

 the perturbations of the heavenly bodies; 

 by the polarization and interference of the 

 waves of light; by the radiation of heat; 

 by electro-magnetic reentering currents; 

 by vibrating chords and surfaces; by the 

 capillary attraction of narrow tubes; and 

 by many other natural phenomena. Hence- 

 forward the work in the world of thought 

 progresses uninterruptedly, each portion 

 continually contributing its aid to the re- 

 mainder. HUMBOLDT Cosmos, vol. ii, pt. 

 ii, p. 302. (H., 1897.) 



87. ADVANCE OF PHOTOGRAPHY 

 Stars Revealed That Are Invisible Even 

 through the Telescope. Celestial photog- 

 raphy is not yet fifty years old; yet its 

 earliest beginnings already seem centuries 

 behind its present performances. . . . 

 The chemical plate has two advantages over 

 the human retina. First, it is sensitive to 

 rays which are utterly powerless to produce 

 any visual effect; next, it can accumulate 

 impressions almost indefinitely, while from 

 the retina they fade after one-tenth part of 

 a second, leaving it a continually renewed 

 tabula rasa. It is accordingly quite possible 

 to photograph objects so faint as to be alto- 

 gether beyond the power of any telescope to 

 reveal; and we may thus eventually learn 

 whether a blank space in the sky truly rep- 

 resents the end of the stellar universe in 

 that direction, or whether farther and far- 

 ther worlds roll and shine beyond, veiled in 

 the obscurity of immeasurable distance. 

 CLERKE History of Astronomy, pt. ii, ch. 

 13, p. 524. (Bl., 1893.) 



88. ADVANCE OF PRIMITIVE MAN 

 From the Stone Age to a Better Stone Age 



The Smoothed and Sharpened Tool Slowly 

 Attained Nature the First Artificer. The 

 next step from the stone age, so far as fur- 

 ther appeal to ancient implements can guide 

 us, is also exactly what one would expect. 

 It is to a better stone age. Two distinct 

 grades of stone implements are found, the 

 rough and the smooth, or the unground and 

 the ground. For a long period the idea 

 never seems to have dawned that a smooth 

 stone made a better ax than a rough one. 

 Mind was as yet unequal to this small dis- 

 covery, and there are vast remains repre- 

 senting long intervals of time where all the 

 stone implements and tools are of the un- 

 ground type. Even when the hour did come, 

 when savage vied with savage in putting 

 the finest polish on his flints, his inspira- 

 tion probably came from nature. The first 

 lapidary was the sea; the smoothed pebble 

 on the beach, or the rounded stone of the 

 mountain stream, supplied the pattern. 

 DBUMMOND Ascent of Man, p. 140. (J. 

 P., 1900.) 



89. ADVANCE OF SOLAR PHOTOG- 

 RAPHY Incessant Record of the Sun by Its 

 Own Light. The first solar light-pictures 

 of real value were taken, and the auto- 

 graphic record of the solar condition rec- 

 ommended by Sir John Herschel was com- 

 menced and continued at Kew during four- 

 teen years 1858-72. The work of photo- 

 graphing the sun is now carried on in every 

 quarter of the globe, from the Mauritius to 

 Massachusetts, and the days are few indeed 

 on which the self-betrayal of the camera 

 can be evaded by our chief luminary. In 

 the year 1883 the incorporation of Indian 

 with Greenwich pictures afforded a record 

 of the state of the solar surface on 340 

 days; and 360 were similarly provided for 

 in 1885. CLERKE History of Astronomy, pt. 

 ii, ch. 2, p. 191. (Bl., 1893.) 



90. ADVANCE THROUGH STRUGGLE 



Sentence of Death on All Who Fail. We 

 find that this hideous hatred and strife, this 

 wholesale famine and death, furnish the in- 

 dispensable conditions for the evolution of 

 higher and higher types of life. Nay, more ; 

 but for the pitiless destruction of all indi- 

 viduals that fall short of a certain degree of 

 fitness to the circumstances of life into 

 which they are born, the type would inevi- 

 tably degenerate, the life would become 

 lower and meaner in kind. Increase in rich- 

 ness, variety, complexity of life is gained 

 only by the selection of variations above or 

 beyond a certain mean, and the prompt exe- 

 cution of a death sentence upon all the rest. 

 FISKE Through Nature to God, pt. ii, ch. 

 2, p. 65. (H. L. & Co., 1900.) 



91. ADVANTAGE OF DIMINISHED 

 LIGHT OF STARS If the entire vault of 

 heaven were covered with innumerable stra- 

 ta of stars, one behind the other, as with 

 a wide-spread starry canopy, and light were 

 undiminished in its passage through space, 

 the sun would be distinguishable only by its 



