COMETS -COMFORTA BLE. 



343 



ones do not appear to follow eacli other according to 

 any law that has been discovered. From 1299 to 

 1 532, all that are mentioned were retrograde ; and 

 five that were observed from 1771 to 1780 were all 

 direct. 



Being quite ignorant both of the size of the comets, 

 and their quantities of matter, we can form no con- 

 clusion as to their effects, even upon the positions of 

 the planets. Hitherto, their influence, if anything, 

 has been very small ; for, within the limits that must 

 be allowed for error, even in the best tables that are 

 calculated upon an approximation, the whole of the 

 irregularities are explainable upon the hypothesis of 

 planetary disturbance alone; and the system ap- 

 pears to have gone on just as if there had been no 

 comets in it. Tliat the comets are formed of matter 

 of some sort or other we know, from the dense and 

 opaque appearance of their nucleus, as well as from 

 the action of the planets upon them ; but, as their 

 action upon the planets has not been great, or even 

 perceptible, we are led to the conclusion that they 

 are not bodies of the same density or magnitude as 

 even the smallest and rarest of the planets. When 

 a comet is viewed through a telescope of considerable 

 power, there appears a dense nucleus in the centre 

 of the luminous and apparently vaporous matter, of 

 which the external parts are composed ; and the 

 opacity of this nucleus varies in different comets. On 

 its first appearance, and again when it recedes, the 

 luminous part of the comet is faint, and does not ex- 

 tend fcir from the nucleus ; but, as it moves on to- 

 wards the perihelion, the brightness increases, and 

 the luminous matter lengthens into a train, which, in 

 some cases, has extended across a fourth of the en- 

 tire circumference of the heavens. But, though the 

 general fact of the increased brightness of comets, 

 and lengtn of their tails, with their approach to the 

 sun, ana the consequent inclination of their motion, 

 has been established, the observations have not been 

 uniform or minute enough for proving what pro- 

 portion the increase of brightness bears to the in- 

 crease of the velocity, and the diminution of the dis- 

 tance from the sun. No doubt, all the comets of 

 which there are well authenticated accounts, of great 

 brightness and length of tail, have passed near the 

 siui in their perihelion. Thus the comet of 1769, 

 which was not a fifth of the earth's perihelion dis- 

 tance from the sun, had a tail of 60 in length, as 

 seen at Paris ; while that of 1759, which was distant 

 more than half the earth's perihelion distance, had a 

 train of only 2 or 3. The length of the tail varies, 

 however, not only with the time at which it is observ- 

 ed, but with the place of observation a difference 

 probably depending on the difference of clearness and 

 purity in the air. The tail of the comet of 1759 was 

 25 long, as measured at Montpelier, in the south 

 of France, and considerably more than that as mea- 

 sured at the Isle of Bourbon, in the Indian ocean. 

 That of 1769 was 60 at Paris, 70 at Boulogne, 90 

 between Teneriffe and Cadiz, and 97 at Bourbon. 

 Generally speaking, they appear to be brighter and 

 larger when seen at sea than on land, and in the 

 warmer regions than in those nearer the poles. 

 When the superstitious fear of comets, as por- 

 tending harm to the inhabitants of the earth, had 

 vanished before the light of philosophy, that light 

 was in some danger of giving rise to fear of another 

 sort fear of physical harm to the earth itself, by the 

 collision of some comet that might cross its path. 

 We have no evidence, however, that such a collision 

 t-ver did happen, either with the earth or with any 

 other planet ; and we have not absolutely correct 

 means of so calculating the place of a comet as to be 

 able to say with certainty that, on a given day, dur- 

 ing a given month, or even during a given yean it 



shall cross the orbit of a planet. The motion of Ure 

 earth in its orbit is, in round numbers, more than a 

 million and a half of miles in a day ; and as Clairault, 

 with all his care, did not come nearer the truth than 

 nineteen days, though the collision of a comet and 

 the earth should be calculated from any known data, 

 the earth might, in fact, be, at the time, far enough 

 from the comet. Indeed, though the fact of the re- 

 turn of two comets be established, namely, Halley's 

 and Encke's, and the return of every one, if not af- 

 fected by physical causes that lie beyond the limits 

 of our present knowledge, has been rendered exceed- 

 ingly probable, yet we can observe them for so short 

 a portion of their courses, and these seem so very apt 

 to be altered, that we ought not to speak of them 

 with anything like the certainty with which we 

 speak of the planets. As far as we have been able 

 to examine them, they appear to obey the same laws 

 as the other distinct masses that make up the known 

 part of the system of the universe. Beyond this we 

 know nothing of their nature ; and as for their effects, 

 moral or physical, we need give ourselves no trouble 

 about them ; for there is not a trace of the existence 

 of such effects upon any authentic record. 



Respecting the hypotheses relating to the struc- 

 ture of comets, and particularly to their tail, profes- 

 sor Fischer, of Berlin, has given valuable information 

 hi Bode's Astronomisch.es Jahrbuch (Astronomical 

 Year-book), 1823, p. 90. See, also, the French edi- 

 tion of Schubert's Astronomy (Petersburg, 1822, vol. 

 2, p. 510). To learn their mathematical relations, 

 see Nouvelles Methodes pour la Determination des 

 Orbites des Cometes, by Legendre (Paris, 1806, 4to) ; 

 and Gibers' Neue Methods die Bahn eines Kometen 

 aus eigner Beobachtung zuberechnen (Weimar, 1797)- 

 La Place's Theorie du Mouvement et de la Figure des 

 Planetes et des Cometes has become rare ; but Biot, 

 hi the Additions to the third book of his Astronomy, 

 p. 185, extracts the part relating to the theory of 

 comets entirely from it. 



COMFORT, POINT. See Point Comfort. 



COMFORTABLE ; a very expressive word among 

 the English, and people of English descent. It is al- 

 so found even in recent French publications, proba- 

 bly carried to Paris by the innumerable English who 

 visit the capital of France. Every nation has not 

 only certain words which cannot be rendered precise- 

 ly by any terms in other languages, but also certain 

 ideas growing out of its customs, wants, c., which 

 do not exist with other nations, and which are the 

 real cause of this peculiar significance of particular 

 words. Such a word is comfortable, which signifies 

 more than a mere physical feeling of gratification. 

 In fact, it has something of the same indefinable and 

 untranslatable character with the word home a word 

 which expresses a vast deal of feeling, of a faithful and 

 tender attachment. A comfortable home is an ex- 

 pression, of which it would be impossible to approach 

 to a translation, in some other languages, for in- 

 stance, in Italian ; as an Italian finds his enjoyment 

 in the open air in his lovely climate, and has little 

 regard for the pleasures of home. Many circum- 

 stances may have co-operated to produce, among the 

 English, their love of comfort, and the means for en- 

 suring it which we find in their houses. In fact, the 

 comforts of an English dwelling surpass every thing of 

 the kind among other nations. We would confine our 

 observation to the dwelling, because, as respects the 

 whole manner of living, the degree of enjoyment is 

 certainly much greater in France. It is always high- 

 ly interesting to study those expressions by which a 

 nation describes its habitual likings or dislikings, be- 

 cause they disclose, at once, the general disposition 

 of the people. Such a one is comfortable. The Ger- 

 man, in a pleasant state of mind, says he feels gemu>h- 



