SCIENTIFIC SIDE-LIGHTS 



Exactness 

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ture 



mented size. If, instead of the planet's light 

 being acted upon by heated air, the planet 

 itself had danced in all directions to and 

 fro, ihe same apparent augmentation of the 

 disk would have ensued. Jupiter, thus 

 quivering, would virtually fill a greater 

 space than if he were still. The case is 

 similar with our dancing atoms. When, in- 

 stead of a motionless atom, we have a vi- 

 brating one, we must make room not only 

 for the atom itself, but also for the distance 

 over which its motion stretches. The case 

 may be further illustrated by a tuning-fork. 

 Motionless as it is at present, its prongs fit 

 into a certain space; thrown into vibration, 

 the prongs strike against their boundaries, 

 demanding more room. TYNDALL Heat a, 

 Mode of Motion, lect. 4, p. 92. (A., 1900.) 



1133. EXPANSION OF WATER IN 

 FREEZING One Instance under General Law. 

 At this temperature [a shade over 39 

 F.] water attains its maximum density. 

 Seven degrees below this temperature, or 

 at 32 F., the liquid begins to turn into 

 solid crystals of ice, which swims upon 

 water because it is bulkier for a given 

 weight. In fact, this halt of the approaching 

 molecules at the temperature of 39 is but 

 the preparation for the subsequent act of 

 crystallization in which the expansion by cold 

 culminates. Up to the point of solidification 

 the increase of volume is slow and gradual ; 

 while in the act of solidification it is sud- 

 den and of overwhelming strength. By this 

 force of expansion the Florentine acade- 

 micians long ago burst a sphere of copper 

 nearly three-quarters of an inch in thick- 

 ness. . . . 



Water is not a solitary exception to an 

 otherwise general law. There are other 

 molecules than those of this liquid which 

 require more room in the solid crystalline 

 condition than in the adjacent molten con- 

 dition. Iron is a case in point. Solid iron 

 floats upon molten iron exactly as ice floats 

 upon water. Bismuth is a still more im- 

 pressive case, and we could shiver a bomb 

 as certainly by the solidification of bismuth 

 as by that of water. TYNDALL Forms of 

 Water, pp. 121-124. (A., 1899.) 



1134. EXPANSION, UNEQUAL, OF 



GLASS Apparent Strength a Source of Weak- 

 ness. In applying heat to glass vessels, 

 thickness is a source of weakness or lia- 

 bility to fracture, on account of the unequal 

 expansion of the two sides, due to inequal- 

 ity of temperature, which, of course, in- 

 creases with the thickness of the glass. Be- 

 sides this, the thickness increases the lever- 

 age of the breaking strain. WILLIAMS 

 Chemistry of Cookery, ch. 2, p. 8. (A., 

 1900.) 



1135. EXPECTATION OF SCIENCE 



VERIFIED Meteorites the Dust of Decaying 

 Comets. The missing comet [Biela's] was 

 next due at perihelion in the year 1872, and 

 the probability was contemplated by both 

 Weiss and Galle of its being replaced by a 



copious discharge of falling stars. The pre- 

 cise date of the occurrence was not easily 

 determinable, but Galle thought the chances 

 in favor of November 28. The event antic- 

 ipated the prediction by twenty-four hours. 

 Scarcely had the sun set in Western Europe 

 on November 27 when it became evident that 

 Biela's comet was shedding over us the pul- 

 verized products of its disintegration. The 

 meteors came in volleys from the foot of the 

 Chained Lady, their numbers at times baf- 

 fling the attempt to keep a reckoning. At 

 Moncalieri, about 8 p. m., they constituted 

 (as Father Denza said) a "real rain of 

 fire." Four observers counted, on an av- 

 erage, four hundred each minute and a half ; 

 and not a few fire-balls, equaling the moon" 

 in diameter, traversed the sky. CLEBKE 

 History of Astronomy, pt. ii, ch. 10, p. 406. 

 (Bl., 1893.) 



1136. EXPECTATIONS, EXTRAVA- 

 GANT, OF NEW INVENTION Proposed 

 Two-mile Telescope. The advantages which 

 were at that period [17th century] supposed 

 to be obtainable only by gigantic length led 

 great minds, as is frequently the case, to 

 extravagant expectations. Auzout consid- 

 ered it necessary to refute Hooke, who is 

 said to have proposed the use of telescopes 

 having a length of upward of 10,000 feet (or 

 nearly two miles ) , in order to see animals in 

 the moon. HUMBOLDT Cosmos, vol. iii, p. 

 63. (H., 1897.) 



1137. EXPECTATIONS OF NATURAL- 

 ISTS DISAPPOINTED Ocean Depths Reveal 

 No Wholly New Life. It seemed probable, 

 before the despatch of the " Challenger " ex- 

 pedition, that when the dredge and the trawl 

 should be successfully employed in depths of 

 over 2,000 fathoms, a new and remarkable 

 fauna would be brought to light. Some nat- 

 uralists thought it even possible that, not 

 only would many genera be found alive that 

 are known to us only by their fossilized 

 skeletons in the Secondary and Tertiary 

 rocks, but that there might be many other 

 new creatures whose anatomy would throw 

 much light on the theories of the evolution 

 of the animal series. But none of the great 

 expeditions that have sailed since the year 

 1874 have yet succeeded in showing that the 

 hopes and wishes of these naturalists were 

 really justified. Altho thousands of species 

 of animals have been described in the vol- 

 umes that have been devoted to deep-sea 

 work, the number of the sub-kingdoms and 

 classes remains the same, and indeed the 

 number of new families and genera has not 

 been increased in any very unprecedented 

 manner. HICKSON Fauna of the Deep Sea, 

 ch. 5, p. 86. (A., 1894.) 



1138. EXPENDITURE, PROFUSE, IN 



NATURE Advantages of Cross-fertilization 

 Species That Have Perished. Profuse ex- 

 penditure is nothing unusual under Nature, 

 as we see with the pollen of wind-fertilized 

 plants, and in the multitude of seeds and 

 seedlings produced by most plants in com- 



