6 44 



HIRKEI.AND. THE NORWEGIAN AURORA POLARIS EXPEDITION, 19021003. 



"The concave side of the crescent, which was the first to enter the field of the telescope, appear,,] ; , 

 be turned towards the west. This peculiarity, which has struck us ever since the beginning of tin 

 observation, has been verified by us on several occasions, on account of its importance, to assure our- 

 selves of it. We have concluded from it that this evening, as also this morning, the tail, which nii"lit 

 to be in the concavity of the head, was apparently directed, in consequence of its great am>atinr, towards 

 the sun('). 



'The same evening, however, but one or two hours later than ourselves, Dr. UARTMANN, observlim 

 the comet through a sweeper of 8 cm. on Mt. Sonnwendstein in Austria, together with Drs. \\'i 

 RHEDEN of Vienna, saw the same appearance of a crescent, but with its concavity turned in the o| 

 direction, namely towards the east (fig. 240) (-). 



"How is this difference in the direction of the head of the comet to be explained? Does it an* 

 from an error of observation? Certainly not! The observations, the one as much as the other, i>o 

 the elements of guarantee necessary to convince us of their exactness, that of HARTMANN corn 



by the data of two other eminent observers, is indisput- 

 able; our own, that we have verified six or seven times in 

 succession, by causing the comet to enter the field of the 

 telescope, and seeing it cross it with its concavity in front 

 is as certain as the other. 



"Is it then possible to make a mistake in such a 

 simple observation as this? It is not a question of mea- 

 suring angles of position, or other slightly complicated 

 observations, where an error might be possible; it is suffi- 

 cient only to see if the crescent enters and moves in the 

 field with its convex or its concave side in front. 



"The hypothesis of an error being thus inadmissible, 

 what could be the cause,- of the contradiction of these two 

 observations? 



"We believe that, as in the appearance of the tail, directed in the morning to the east /twin/* I 

 sun, it is only a question of perspective. In reality, according to the explanation that we have t;iun 

 of the curious shape presented by the comet at Athens on the evening of the aoth May, the axi> 

 the head was probably directed at that moment approximately towards the earth; in these comb 

 the nucleus ought to be projected near the top of the outline, and appear to touch it; the nehiild.-ih 

 of the tail, which often extends a little in front of the nucleus, became invisible, and the tail ought t" 

 disappear almost completely in the telescope. 



"In this hypothesis, the difference of the two observations might then be explained as the result > 

 a change in the apparent direction of the convexity of the head in consequence of the rapid rotati, 

 of its axis, relatively to the earth; and this relative rotation is evidently the result, on the OIK hand, < 

 the at first very rapid movement of the comet, on the other, of the contrary movement of the earth.' 

 According to ANTONiADNi( 3 ), the observations of Eginitis must be altogether wrong, as he < 

 not find them verified by the observations of WOOD and HARTMANN, as seen in the following si 

 fig. 241 taken from Antoniadni's paper. 



We do not think there is sufficient reason in this statement for disqualifying the observation- 

 Eginitis. 



N 



Kig. 239 



(') Aslr. Nachr., 4414 and 4431 Comtes rendus t. CL., pp. 1408 and 1578. 

 (') Drawing by Dr. HARTMANN, published in Astr. Nachr., 4431. 

 (") "Ciel et Terre", December 1911, p. 435. 



