OF ARTS AND SCIENCES. 147 



hibited the model %f another instrument, constructed by Mr. 

 Nichols, for the division of an angle into any number of equal 

 parts. 



Professor Peirce also presented the computation of the orbit 

 (elliptical) of Petersen's comet, made by young Safford, now 

 thirteen years of age, showing its period to be 382,000 years. 

 He stated that Safford was employed only fifteen hours in the 

 computation. 



Professor Peirce likewise made a communication, in which 

 he gave reasons for his belief that all the comets seen by us 

 are component parts of our solar system, drawn from the fact 

 that their orbits are none of them decidedly hyperbolical. He 

 showed that few comets could enter the solar system except 

 in orbits of a manifestly hyperbolic form,' derived from the 

 motion of our system in space. 



Three hundred and eighteenth meeting. 

 April 4, 1849. — Monthly Meeting. 



The President in the chair. 



Mr. Everett read a letter from M. Leverrier, in relation to the 

 discovery of the eighth satellite of Saturn^ He also exhibited 

 the comet-medal awarded by the king of Denmark to Miss 

 Mitchell, which had just been received, and presented a print- 

 ed copy of the correspondence which had been held in rela- 

 tion thereto. 



Professor Peirce read a letter from Mr. S. C. Walker, contain- 

 ing a comparison of his ephemeris of Neptune with the latest 

 observations on that planet, showing a variation from his calcu- 

 lations of only the fraction of a second. He also adduced fur- 

 ther reasons for his opinion that the known comets belong to 

 our solar system, drawn especially from the tendency of their 

 orbits in respect to the plane of the ecliptic. His attention 

 had been drawn to the obvious error of Laplace's argument 

 upon this point by Dr. B. A. Gould, Jr. ; who has made a 



