44 



ASTRONOMICAL PHENOMENA. 



tically over Omicron, in the Great Bear's nose, 

 and during the night retreated almost in the 

 apparent direction of the tail. At about 11 

 o'clock the tail could be traced for fully ninety 

 degrees ; it consisted of a curved brush of light 

 bending over to the direction of the two point- 

 ers. The light of this short brush was ex- 

 tremely diffuse on the western side ; towards 

 the eastern side a long narrow ray shot out, 

 extended over the zenith, and passed through 

 Dracnnis, where it again enlarged, and became 

 very faint, but could be traced several degrees 

 beyond an imaginary line, which would join a 

 Lyras and Arcturus. The appearance of the 

 comet in my second Newton's reflector was on 

 the 2d inst. very like a broken fan, supposing 

 the two lower ribs to be considerably curved, 

 and the height of the fan small in comparison 

 with its width. The nucleus, which was situ- 

 ted at the joint of the ribs, was extremely small 

 and elliptical, the longer axis of the ellipse 

 being in the direction of the length of the tail. 

 Last night the, fan-shape of the coma was much 

 more distinct and more generally filled with 

 light ; but there were several irregular brighter 

 rays within it. The light of the coma and en- 

 velope is much more diffuse and less brilliant 

 than Donati's comet of 1858. I made an at- 

 tempt on the 2d to obtain a photograph of the 

 comet in the focus of my reflector ; but not the 

 slightest impression was produced by an expo- 

 sure of two minutes, although a fixed star was 

 clearly depicted. Yesterday, the 3d, I made 

 several attempts to photograph the comet by 

 means of Rosse's No. 3 portrait lens mounted 

 on the top of my telescope, and carried round 

 by clockwork not the slightest trace of the 

 comet was depicted in fifteen minutes, although 

 the fixed stars were depicted. As Donati's 

 comet was photographed by similar means in 

 seven seconds, (not by myself,) it follows that 

 the present comet is considerably less actinic 

 than Donati's. WABBEH DE LA RUE." 



Other attempts were made to photograph 

 the comet, but without success. The contigu- 

 ous stars left a strong impression on the pre- 

 pared glass, but the comet itself left no trace 

 of its presence. 



M. Le Verrier, of Paris, addressed the Academy 

 of Sciences, as follows, respecting this comet: 



"We do not know this comet; it is the first 

 time it visits us, and those who have endeavor- 

 ed to predict its course, determine its distance 

 from the earth, and measure its tail, have either 

 deceived themselves or the public. Three ele- 

 ments are necessary to calculate the orbit of a 

 comet : first, the exact position of the star ; 

 then its velocity ; and, lastly, the variation of 

 velocity produced by the mass of the sun. I 

 caused the comet to be observed on the 30th 

 of June, and then on the night of the 1st and 

 the morning of the 2d inst., in order to deter- 

 mine the variation of velocity. These three 

 observations would have followed too closely 

 npon each other for the calculation to be at- 

 tempted, were it not that the comet moves very 



rapidly. On the 3d, at 10 A. M., M. 

 brought me the result of his calculations, and 

 we then obtained an insight into the orbit of the 

 comet. Mr. Hind has since sent me the orbit 

 calculated by the English astronomers, which 

 perfectly agrees, in all but two minutes, with 

 our results. It is now positive that this is not 

 Charles V.'s comet; and, moreover, it resem- 

 bles none of those already observed. This cir- 

 cumstance will contribute not a little to throw 

 confusion upon the little we know of these 

 erratic bodies. I cannot yet say whether this 

 comet is periodical or not ; its orbit up to this 

 day has been too cursorily determined to enable 

 ns to pronounce it elliptical, parabolical, or even 

 hyperbolical. At any rate, appearances are 

 against its return, for the orbit is nearly per- 

 pendicular to the plane of the ecliptic, while 

 those of periodical comets usually form a very 

 small angle with that plane. It is only now we 

 can determine the distance of the comet from 

 the earth, and the length of its tail. On the 

 30th of June the line joining the centre of the 

 sun with that of the comet made an angle of 

 four degrees with that joining the centres of 

 the sun and earth, the length of which is 

 known. The angle which this line formed 

 with the visual ray, drawn from the eye of the 

 observer to the centre of the comet, was 24. 

 The triangle thus formed may, therefore, be 

 calculated, and it gives us the distance of the 

 comet from the earth, amounting to between 

 6,000,000 and 7,000,000 of leagues, (about 17,- 

 000,000 of miles English.) The length of the 

 tail might be similarly calculated. The comet 

 is rapidly moving away from us, and it is there- 

 fore not surprising that its brilliancy has di- 

 minished. On the 10th it will be equally distant 

 from the sun and earth ; we shall soon lose 

 sight of it, and astronomers only will be able to 

 follow it for a month longer. It presents a 

 singular peculiarity. M. Chacornac has studied 

 the nucleus with one of M. Foucault's tele- 

 scopes of a diameter of forty centimetres ; in- 

 stead of its being hollow like the half of an egg- 

 shell, like most of the comets already observed, 

 it presents the appearance of a sun composed 

 of fireworks, the bent rays of which burn in the 

 same sense. Moreover, the comet has not drawn 

 nearer to the sun. These are all circumstances 

 calculated to introduce great complications into 

 the theory of comets." 



The comet as seen at Rome is described by 

 Father Secchi in a communication to the French 

 Academy. The most interesting fact which he 

 relates is that on the 30th of June the polari- 

 zation of the light of the tail and of the rays 

 near the nucleus was very strong, and could be 

 distinguished by the polariscope in bands, while 

 the nucleus itself presented no traces of polari- 

 zation, even with Arago's polariscope with a 

 double colored image. But, however, on July 

 3d, and the following days, until the 7th, the 

 nucleus, in spite of its extreme diminution, ex- 

 hibited sensible indications of polarization. 

 Father Secchi considers this fact of great iin- 



