Captain Hall's comet seen at Valparaiso. 6 1 
90 — 77, 90 — 7 r" and V', the angle opposite to 90 — 7 r", and 
also in the spherical triangle formed by 90 — 77, 90— 77 ; and 
V, the angle opposite to 90—77'. 
These angles are 
152 0 38' 9", which gives the inclination 73 0 1 9 1 50" 
132 5 1 which gives the inclination 73 11 47 
Now, if the orbit were an exact parabola, and the observa- 
tions perfectly accurate, the above quantities ought, in conse- 
quence of the exactness that has been used in the computa- 
tion, to agree to a second. Hence is seen the unavoidable 
errors arising from these two causes jointly. It is probable, 
that the deviation from a parabola has no sensible effect in 
the present case. 
With the mean value 152 0 43' 3" we get the place of the 
node 48* 24' 41", and the place of perihelion =7’ 29 0 6 ' 47". 
There evidently appears an irregularity in the three last 
right ascensions observed April 29, May 1 and 3. It is possible, 
that this happened in consequence of the difficulty of observ- 
ing the comet from its faintness : if so, each of the observa- 
tions may partake of that irregularity, and the inaccuracy of 
the observation of May 3, may have affected the elements. 
This might have been avoided, by combining a greater 
number of observations in correcting the approximate ele- 
ments, but the advantage would not, probably, have repaid 
the additional labour. 
The remark on these latter observations, must not be un- 
derstood to imply, in the smallest degree, a defect in observ- 
ing; on the contrary, the general exactness of the observations 
appears highly creditable to the observers, and requires no 
