CHR 



CHR 



the density of the air, the correspondent 

 change per day, in the rate, may be two 

 seconds and a half, or about one second 

 per inch. Hence it may happen that a 

 capital time-keeper shall indicate a more 

 steady rate from week to week than from 

 day to day. 



The causes of imperfection in chrono- 

 meters, which still call for farther exer- 

 tions of sagacity in our artists, are, 1. The 

 spring gradually tires or falls off from its 

 strength, and neither the law of this vari- 

 ation nor its remedy are known. The ef- 

 fects of this change are, that all the ad- 

 justments are disturbed by it. 2. There 

 is great reason to apprehend that the ex- 

 pansion-bars of brass and steel do change 

 in Jheir relative powers of flexure by 

 their continued action on each other, 

 though it is probable they settle at last. 

 3. The wear of the acting parts is uncer- 

 tain, and will affect the time of striking 

 out the detent and the arc of impulse. 4. 

 No certain rules have been given, or are 

 perhaps known, for making all the vi- 

 brations equal in time. If we suppose 

 the long and short vibrations to be at first 

 adjustable, with certainty, to equal times, 

 not only for the extremes, but for all the 

 means or intermediate arcs, it will not fol- 

 low that the falling off from wear or from 

 tiring, or from change in the balance, will 

 continue to be accompanied by the same 

 isochronism. 5. The best artists find 

 very great difficulty in adjusting a pocket 

 chronometer for all positions, preserving 

 at the same time the other needful ad- 

 justments. See ESCAPEMENT, HOROLOGT, 

 PENDULUM, TBAIN, and the articles 

 thence referred. 



CHRYSALIS, in natural history, a state 

 of rest and seeming insensibility, which 

 butterflies, moths, and several other kinds 

 of insects, must pass through, before they 

 arrive at their winged or most perfect 

 state. The first state of these animals is 

 in the caterpillar or reptile form ; then 

 they pass into the chrysalis-state, where- 

 in they remain, immoveably fixed to one 

 spot, and surrounded with a case or co- 

 vering, which is generally of a conical 

 figure ; and, lastly, after spending- the 

 usual time in this middle state, they throw 

 off the external case wherein they lay 

 imprisoned, and appear in their most per- 

 fect and winged form of butterflies, or 

 flies. See CATERPILLAR. 



CHRYSANTHEMUM, in botany, a ge- 

 nus of the Syngenesia Polygamia Super- 

 flua class and order. Natural order of 

 Composite Dioscoidese. Corymbiferae, 

 Jussieu. Calyx, hemispherical, imbricat- 

 ed ; the marginal scales membranaceous j 



pappus margined; receptacle naked. 

 There are twenty -seven species. One of 

 these, the Chrysanthemum leucanthe- 

 mum, or ox-eyed daisy, has been intro- 

 duced from Europe, and become natura- 

 lized in the United States ; it has in fact 

 become one of the most troublesome and 

 pernicious weeds which infest our coun- 

 try. It covers hundreds of acres of 

 ground with its white flowers, in the 

 month of June. 



CHRYS1S, golden fly, in natural history, 

 a genus of insects of the order Hyme- 

 noptera. Mouth horny, projecting; lip 

 much longer than the jaw, which is li- 

 near, membranaceous, and emarginate at 

 the tip ; no tongue ; feelers four, un- 

 equal, filiform ; antennae short, filiform, 

 of twelve articulations, the first longer ; 

 body gilt polished ; abdomen arched be- 

 neath, with a scale on each side ; tail 

 generally toothed ; sting pungent, near- 

 ly concealed ; wings flat. These are ge- 

 nerally found in the holes of old walls; 

 There are more than thirty species. 



CHRYSITRIX, in botany, a genus of 

 the Polygamia Dioecia class and order. 

 Natural order of Calamarix. Cyperoideae, 

 Jussieu. Essential character: herma- 

 phrodite ; glume bivalve ; corolla of nu- 

 merous setaceous chaffs ; stamina many, 

 solitary, between the chaffs ; pistil one : 

 male as in the hermaphrodite ; pistil one. 

 There is but one species ; viz. C. capen- 

 sis, a perennial plant ; native of the Cape 

 of Good Hope. 



CHRYSOBALANUS, in botany, a ge- 

 nus of the Icosandria Monogynia class 

 and order. Natural order of Pomaceae. 

 Rosaceae, Jussieu. Essential character: 

 calyx five-cleft ; petals five ; style late- 

 ral ; drupe with a five-furrowed, five- 

 valved nut. There is but one species : 

 viz. C. icaco, cocoa plumb, a shrub about 

 eight feet high. Native of the Caribbee 

 islands, and the neighbouring continent 

 near the sea. 



CHRYSOBERYLL, in mineralogy, a 

 species of the flint genus. Its chief co- 

 lour is asparagus green, passing on the 

 one side into an apple-green, mountain 

 green, and greenish white : on the other 

 side it passes through light olive and oil 

 green into yellowish grey, which inclines 

 to brown. It occurs but seldom crysta- 

 lized, and then the crystals are small, ex- 

 ternally shining, internally splendent, and 

 intermediate between the resinous and 

 vitreous. It is brittle, not easily frangi- 

 ble ; specific gravity from 3.6 to 3.8. Be- 

 fore the blow-pipe it is infusit'.e without 

 addition : it is found in Brazil, m the 

 sands of Ceylon, along with rubies and 



