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AMERICAN ASSOCIATION FOE THE ADVANCEMENT OF SCIENCE. 



[1855- 



the freezing point. He would ask if there Tvcre any such. Prof. 

 Henry said that during the past winter be bad been struck with the 

 fact that pieces of ice wrapped in a cloth were frozen to it, although not 

 one oiit of the several thermometer - would go down to 32. It appeared 

 from this, as from the old obserTation of La Place, who found that 

 the ice surrounding the worm through which they were transmitting 

 gases was soon frozen to the worm, that melting ice produced a cer- 

 tain degree of cold. The temperature of a mixture of ice and .alcohol, 

 in the form of wine, brandy, &c., was lower than 32°. Hence ice and 

 alcohol was a freezing mixture. 



Professor Agassiz explained the different kinds of ice. First was 

 that produced by the freezing of the surface of the water and suc- 

 cessive layers of water beneath it, a laminated schistose mass. Into 

 this bubbles from 'the bottom of the pond were frequently frozen, 

 and when it was subjected to the action of the sun the bubbles be- 

 came heated, melted the ice around them, and rendered it of no 

 marketable value. It would therefore be worth while for ice gatherers 

 to cover their ponds with cloths, or something which would pre- 

 vent these bubbles from rising. Glacier ice was formed like pud- 

 ding stone ; compact masses being cemented together, so that when 

 you exposed a large lump of glacier ice to the heat of the sun it 

 would crumble in pieces. It was like the decomposition of con- 

 glomerate ; we had ice sand. Icebergs could be determined to be 

 derived from glaciers, and not to be the frozen surface of the ocean, 

 by their conglomerate composition. Pebbles in glaciers becoming 

 heated melted the ice beneath them, and quarried their way down 

 to where the heat of the sun could not reach them. The pot holes 

 formed in this way were soon covered with a thin film of ice, but 

 it was only during the protracted cold of winter that they were 

 frozen through. 



ASTRONOMY. 



Solution of the Adams Prize Problem for 1857 — Part First. By 

 Prof. Benjamin Pierce. — The problem has for its subject the Motion of 

 Saturn's Rings, allowing them to be solid or iluid, concentric or 

 eccentric. He reserved the consideration of solid rings of immoveable 

 parts for a meeting of the Mathematical section, when by use of 

 formula he would prove it untenable. Can it be made up of a mass 

 of satellites moveable among themselves ? Then they must be in 

 continual motion among themselves ; revolving among themselves 

 about their common centres of gravity, perpetual collisions ere this 

 would have reduced them to powder. We assume now that the rings 

 are fluid. Then they may vary in form. It was first shown that 

 they had varied by Otto Struve. The diameter of the outer part of 

 the ring is not known to have changed. The inner edge is contracting 

 as it seems to me. Huygens, in 1657, made it (allowing for the irradi- 

 ation of his telescope) 6.5" Huygens and Cassini, in 1695, made it 

 6"; Bradley, in 1719, 5.4''; Herschell, in 1799, 5"; Struve, senior, 

 in 1826, 4.36''; Encke and Galle, in 1838, 4.04"; and Otto Struve, 

 in 1851, 3.67" Does it decrease uniformly ? I think it is deer-easing 

 more rajiidly, and the present rate will bring the ring to an end, in 

 certain parts of it, in about 80 years from now. I will show in the 

 meeting in section that the planet does nothing either to maintain or 

 destroy the equilibrium of the ring. The satellites tend to maintain 

 it in place. The ring is not gas ; its density is nearly that of water. 

 If the zodiacal light be a gaseous ring of the earth, it would need 

 some solid parts to give body to it. May that gas be the atmosphere 

 around an infinity of small masses revolving about each other .and 

 about the earth ? May there not be collisions among these revolving 

 masses that throw down parts of them to the earth ? Is not that as 

 good a reservoir of meteors as the moon? Their melted state seems 

 to lead us to a lunar volcanic origin ; but unless some lunar volcano 

 pointed expressly at the earth were put in furious operation, such a 

 bombardment could not hit the earth with one in ten thousand of 

 its projectiles. Prof. Pierce is inclined to adopt this hypothesis. The 

 action of Saturn would tend to bring a solid inflexible ring against 

 itself. 



Dr. Peters would conclude from the data of Prof. Pierce, that the 

 cataclysm of the contact of the ring would occur about 1893 instead 

 of 1935. But Struve has strangely omitted the observation of Bessel 

 made with the heliometer, a more accurate instrument than the filar 

 micrometer used by Struve at Dorpat, and by Encke and Galle at 

 Berlin. By using these data the time would be reduced so that the 

 present generation may hope to see it. 



Prof. Pierce thought the data too imperfect to use in a calculation 

 of time. It does not appear certain that it is not a vibration which 



will go on in due time to recede again from the planet. But of this 

 we can as yet obtain no evidence. 



071 the Asteroid Planet. By Prof. S. Alexu7ider. — By a most mas- 

 terly use of circumstantial evidence of a delicate naluie, Prof. AUx- 

 andcr has arrived at almost a certainty that in the s-pace between 

 Mars and Jupiter once revolved a planet a little more than 2.8 times 

 as far from the Sun as our earth. The equatorial diameter was about 

 70,000 miles, but the polar diameter only 8 miles ! It was not a globe 

 but a wafer — nay a disc of a thickness of only 1-9,000 of its diameter. 

 Its time of revolution was 3.098 days, say 3 days 15 hours 45 minutes. 

 The inclination of its orbit to the ecliptic was about 4°. It met a fate 

 that might have been anticipated from so thin a body, whirling so 

 furiously, for its motion on its axis was l-16th of its velocity in its 

 orbit, say, 2,477 miles per hour. It burst as grindstones and fly- 

 wheels sometimes do. M'e have found 35 fragments of it and call 

 them asteroids. When it burst some parts were moving 2,477 miles 

 per hour faster than the centre did, and some as much slower ; that 

 is, some parts moved 4,954 miles per hour faster than the others. 

 These described a much larger orbit than the planet did, and the 

 place where it burst was their perihelion. Others described a smaller 

 orbit, because they left that point with a diminished velocity ; it was 

 their aphelion. Some flew above the orbit of the planet and had their 

 ascending node. Others flew below, and it was their descending node. 

 They seemed to go almost in pairs. Two went vei-y far out of the 

 plane of the orbit, so that they pass the limits of the zodiac, and it 

 is found that the ascending node of IS correspond nearly with the 

 descending node of 17, so nearly even were they distributed. And 

 thin as was the planet, it had not cooled so much at the time of the 

 explosion that none of the fragments could assume a spherical form. 



The planet's place was first to be found. Three or four independent 

 processes were used for this, and they agreed surprisingly. He inter- 

 polated it as a lost term in a geometric series, from Mars to Saturn, 

 for the first approximation. He compared it with Saturn and Jupiter, 

 and with Mars and .Jupiter. He found where a planet would be 

 dropped off in the successive cooling and contracting of the solar 

 system. And he compared its orbit for size and ellipticity with those 

 of the asteroids. Some of them gave solutions very far from the 

 average. Rejecting these, the others coincided with previous deduc- 

 tions and with each other surprisingly. Its day he found by Kirk- 

 wood's analogy. Its equatorial diameter was the result of two calcu- 

 lations, one of which would inevitably give a result too large, and the 

 other too small, in all cases when the planet did not explode at its 

 equinox, when it would be exact. These numbers were 78,425 and 

 68,646 miles. A just comparison gave 70,470. But we can follow 

 these calculations no further. 



It is curious to see how the history of this planet verifies the theory 

 of La Place, that a heavenly body must be either nearly a sphere or 

 a disc, and that the latter must be unstable. And this reminded 

 Prof. Alexander again to allude to the earth's ring — the zodiacal 

 light. He had long been convinced that the moon could not be the 

 only satellite thrown ofl' by our planet in taking on its present form, 

 but knew not where to look for the rest. A more careful calculation 

 of the data furnished by the Rev. Mr. .Jones, had given him for the 

 diameter of the ring 17,000 miles, and a time of about half a day for 

 rotation. And curiously enough, half a day was the time that had 

 been assigned by a previoas calculation for the revolution of an 

 ajrolite round the earth; 



iSolar Bed Flames. — Professors Alexander and Henry were observ- 

 ing together upon this phenomenon. It is now settled that this red 

 light comes from the edge of the sun, and can be seen only by the aid 

 of peculiar colored light. But using a large Fresnel lens, and throw- 

 ing the image two inches in diameter on wood, it took fire, and be- 

 hold in the smoke I saw the red flames of the sun as seen seventeen 

 years before ! And strange to saj', they Avere only visible in the glass 

 which showed the red flame in the sun. When the eye becomes tired 

 by gazing on bright white light, the flame of a candle is invisible 

 through all other screens but that kind ; in that it is crimson. It is 

 probably a subjective coloring existing in the eye, and is the result of 

 white light. 



Graptolites. — Prof. James Hall gave some notes upon the genus 

 Graptolithus. The genus Graptolithus includes now about ten species 

 of fossil remains, most of which are American, and of some of which 

 Prof. Hall has recently found better specimens than ever before. 



