SCIENCE. 



353 



SCIENCE: 



A Weekly Record of Scientific 

 Prog r ess. 



JOHN MICHELS, Editor. 



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SATURDAY, JULY 30, 1881. 



There appears to be an open question between 

 Professor Ormond Stone, of Cincinnati, and Mr. 

 Rock, of Washington, as to whether the nucleus of 

 Comet b, 1 88 1, divided on the night of the 6th in- 

 stant. 



Both astronomers appear to have observed the 

 comet at the same time, but have recorded somewhat 

 different results. 



On reference to "Science," July 16th, page 334, 

 will be found a statement of what Mr. Rock saw, as 

 follows : 



On the 6lh of July the comet was observed by Mr. Rock of the 

 Naval Observa'ory : 



" A bright tongue of light about on; revolution long in direction 

 of tail, with a slight node near end and curved." 



In explanation of this Mr. Rock said: " I observed the comet 

 at the time of its lower culmination about twenty minutes after 

 midnight. T e nucleus did not appear to be divided, but a bright 

 band streamed out in the direction of the tail. This band was 

 about fifteen seconds of the arc in length. Near the end of it was 

 a bright spot, and that portion of the band extending beyond it 

 was curved in the same general direction as the tail, but in a some- 

 what shorter arc." 



And then referring to Professor Stone's report of a 

 division of the nucleus, he adds : 



" It is possible that the observer at Cincinna'i was not able to 

 distinguish the band of light which I saw uniting the nucleus and 

 the node, and so concluded that he saw two nuclei. When I first 

 observed the comet, on June 28, the coma was apparently homo- 

 geneous as it also was on July 2. On June 28, howcve-, there 

 were two spurs of light spreading away from the opposite sides of 

 the head like angel's wings. On July 2, I did not observe these 

 at all or they wert very faint. On -July 6, I observed the appear- 

 ance that I have described. It may be that this was the same 

 thing that I saw on June 28, observed from a different point of 

 view. It is not improbable, however, that the nucleus has really 

 divided. Comets appear to have a tendency to do that." 



In another part of this issue will be found a letter 

 from Professor Stone, reiterating his former claim of 



having observed a division of the nucleus of this 

 comet on the night of the 6th instant. 



" He states that on the 6th of July, during obser- 

 vations made between 10 p. m. and 3 a. m., he saw 

 a bright red jet projected from the nucleus into the 

 dark region on the side of the nucleus opposite the 

 fan, which was totally different in appearance from 

 those usually seen. There was a dark line separating 

 it from the nucleus. During the first few minutes a 

 decided change took place. The jet seemed to sepa- 

 rate and form a nucleus of ifs own, so that for a time 

 the comet appeared double." 



It may assist in a solution of this subject if our 

 readers inspect the continuation of the interesting 

 drawings of this comet, made by Professor Edward S. 

 Holden, to be found on another page of this issue.* 



The drawings we published last week showed the 

 appearance of the comet on 24th, 25th, 26th, 27th, 

 28th and 29th of June, and the nights of the 8th and 

 nth of July. Those presented in this number give 

 views of the comet for the nights of the 13th, 14th, 

 17th and 1 8th of July. 



The drawing for the 1 ith of July is interesting as 

 showing " a dark narrow channel between the follow- 

 ing side of the nucleus, and the envelopes," but, added 

 Professor Holden, " the nucleus is not double." But 

 the drawing we offer this week for the 18th instant, is 

 quite remarkable as showing a decided division of the 

 nucleus, and Professor Holden remarks in his note to 

 it, " The nucleus is double (it has not been pre- 

 viously)," and those who inspect this drawing will find 

 two nuclei. 



The drawings of Professor Holden and the obser- 

 vations of all who have watched this comet, show 

 conclusively that the form of the nucleus changed 

 very rapidly and continuously, and as we have the 

 best evidence that the nucleus divided on the 18th in- 

 stant, it makes it very probable that a similar phe- 

 nomenon occurred on the 6th of the same month, es- 

 pecially as Professor Stone is an accomplished 

 observer, and not likely to be mistaken in his descrip- 

 tion of the optical appearance of a celestial object. 



An experiment illustrating "fatigue" in the sense of 

 hearing (corresponding to fatigue of the retina) has been 

 described by Herr Urbantschitsch. Two tubes are adapted 

 to the ears, and adjusted, so that a given tuning-fork is 

 heard equally on both sides. Now strike the fork strongly, 

 and let it sound a little through one tube ; then deaden it 

 somewhat by touching. The ear on that side fails to catch 

 the weakened sound, but on transferring the fork to the 

 other ear, the sound is heard distinctly. If the weaker tone 

 presented be of different pitch from the stronger, it is heard 

 on both sides equally. The failure of sensitiveness in the 

 other case is very transient. 



* On account of delay in engraving these drawings, they are reserved 

 until next week's issue. 



