4701 Royal Astronomical Society. 



a living animal, the positive pole being placed now above, now below, 

 so that it may be supposed that the current passes in the two cases 

 in opposite directions as regards the nervous filaments distributed in 

 the muscles. He then points out that the effects of a current 

 directed downwards, in the direct course of the nerves, are a strong 

 contraction of the muscle traversed, and also of the muscles of the 

 leg below ; while the effect of a current in the opposite, or inverse 

 direction, is pain, together with contractions less violent and always 

 confined to the muscles traversed. The contractions (especially of 

 the parts below) indicate a current of nervous force propagated to- 

 wards the muscles, wliile the pain indicates a current towards the 

 nervous centre. Now, bearing in mind that it has been proved by 

 direct experiments that an electric current traversing a muscle never 

 quits the muscular fibre to enter the nervous filaments, it seems clear 

 that the phenomena just spoken of are exclusively owing to the in- 

 fluence exerted by the electricity passing through the muscles on 

 the nervous force contained in the nerves ; and also that this nervous 

 force acts peripherad or centrad according to the direction of the 

 electric current which excites it. The great importance of the con- 

 clusions drawn from these experiments consists in this, that they lead 

 to the same law which establishes the analogy between nervous force 

 and the electrical discharge of fishes. The paper concludes with 

 some further considerations intended to confirm this law. 



ROYAL ASTRONOMICAL SOCIETY. 

 [Continued from p. 31].] 



Jan. 1 1, 1850.— On the Past History of the Comet of Halley. By 

 Mr. J. R. Hind. 



It is well known that the periodicity of the remarkable comet 

 which bears the name of Halley was inferred by that astronomer 

 from a comparison of three sets of elements, calculated on observa- 

 tions of the comets of 1531, 1607 and 1682. When his table of 

 cometary orbits was first published. Dr. Halley says he was content 

 to hint at his conjectures respecting the identity of the comets of 

 those years as having some degree of probability, and to advise pos- 

 terity carefully to watch for its return about the year 1758. At a 

 subsequent period, an examination of the catalogues of ancient 

 comets showed that three others had preceded those already men- 

 tioned, " manifestly in the same order and at like intervals of time, 

 viz. in the year 1305 about Easter; in the year 1380, the month 

 unknown ; and, lastly, in the month of June 1456 ;" and on making 

 this discovery Dr. Halley says he became much more confirmed in 

 his former opinion. Want of data, however, prevented his ascer- 

 taining beyond doubt that the comet of 1682 had appeared in any of 

 the three years 1305, 1380 or 1456, and he had little or nothing 

 but equality of intervals, on which to found his belief. 



M. Fingre, after collecting together the immense mass of records 

 from which his great work the Cometographie is constructed, was 

 enabled to convert into a cei-tainty Halley's supposition respecting 

 the appearance of his comet in 1456. Two definite observations of 



