218 Comets. 



be a secreting surface either in the foot or easy of access to it ; 

 and that secretion hardens and blackens by exposure to the 

 water. The threads are attached to the shell, and have no 

 connection with the internal economy of the animal. The 

 byssus spun by the Pinna has been used with silk, and spun 

 into some articles of dress. That of the great horse-mussel is 

 exceedingly fine, and if it could be obtained in sufficient abun- 

 dance might be used in commerce. 



In conclusion, could not a series of experiments be made on 

 the mussel {Mytilus edulis), to discover how it spins its cable, 

 and where it gets the material ? By discovering this, we could 

 then with certainty understand how the Lima and other shells 

 make their nest, for they also use silken fibres to bind the 

 materials of which their house is built. 



COMETS. 



AN ACCOUNT OF AIX THE COMETS -WHOSE OEBITS HAVE NOT BEEN CA1CTT1ATED. 



BY G. F. CHAMBERS. 



{Continued from page 384, vol. iv.) 



663. On September 27 a comet 2' long was seen near £ 

 Bootis. On September 29 it had disappeared. — (Ma-tuoan- 

 lin.) 



667. On May 24 a comet was seen in the N.E., between 

 Auriga, the Pleiades, and Taurus. — (Gaubil.) On June 12 

 it disappeared. — (Ma-tuoan-lin.) 



668. In May or June a comet was seen for a few days in 

 Auriga. — (Do Mailla, vi. 145.) Is it certain that this comet differs 

 from the preceding? — (Pingre, i. 331.) 



676. [i.] On January 4 a comet 5° long was discovered to 

 the S. of a and £ Virginis. — (Ma-tuoan-lin.) 



676. [ii.] " In the month of August a comet showed itself 

 in the E. for three months, from the timo of cock-crowing till 

 morning. Its rays penetrated the heavens; all nations beheld 

 with admiration its rising; at length, returning upon itself, it 

 disappeared/' — (Anastas, Rietoria EcclesiasUca } Paul Diacon. 

 v. 31.) On September 4 a comet appeared near to a and fi 

 Geminornm ; it moved towards the N.E. Its tail, at first 

 3 1 long, afterwards increased to 30°, and pointed towards X 

 and fj, Ursaa Majoris. On November 1 it had disappeared.— 

 (Ma-tuoan-lin ; Gaubil.) 



