■: -^ \ J—'— ^ - 



■ :^^S-,,'^- 



I 



ISO 



MATHEMATICAL and 



=C=E 



Sine 



o 



t'. - - - 9,086437 



Sub. from 



a;,. aS obluiuity of the ecliptic. 



16*^ --' 



Rem, 10-. a?' '"i;"^. 



4,Sinc - - - 87. 8^ 20' 



9,452060 

 9,999458 



.Rad. ==Sme 16. 26-^CR- 9.45T5i8 



18,698340 



9,981886 



Rad.+Cofi. 87". ?^ ^o'' 

 .Cofme - - 16. 26. 



Therefore, by calralation from? ^^^o^ .^^^ . 



fhr fhcorv, "wc have S ^ ^^ ^^r 



But by Mr. Mcfiicr's obfcrvation, _ a?^- 57i ._ ^ S- S5: 



The difference in right .fcenfion is, 0°. I'X and 0°. 30 i in declination. 



16°. a6' 



H 



M. Meffi 



entirely agrees with the magnitude I have affigned the 

 Comet's orbit, and likewife with the time and place of the 

 perihelion; but the inclination of the orbit ought perhaps 



to be increafed four or five minutes. I am, 



Ever yours, &c. 



Decemkr 2, ^ 77°- D. RITTENHOUSE. 



To Rev. Dr. Sunn. 



POSTSCRIPT. 



Mr. Rittenhoufe, when he wrote his firft paper, ex- 

 preffed his hopes of obtaining a further confirmation ot his 

 theory of this Comet's motion, by feeing it on its afcent 



from the perihelion. But it was not then feen (fo far as 



we have yet heard) by any perfon in America. This d.f- 

 appointment, however, he did not afcnhe to anydcfeft in 

 a theory which he had endeavoured to eftabhfh from the 

 befl: principles, and with great labour of calculation, but 

 to the difficulty of finding a body of fuch fmall fize in the 

 lieavens; efpecially with fuch a large unwieldy refrador, 

 as he himfelf was obliged to ufe. The account, there- 

 fore of M. Meffier's obfervation, who faw the Comet ten 

 or twelve days fooner than we did here, being fo accept 

 able to him, (as it gave a further opportunity of confirm 

 inghis theory by the above paper of December 22d) I 



ima-incd that any account of the Comet, after its return 

 <2 from 





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