218 J. C. Watson on the Elements of the Orbit of a Comet. 
the isthmus from Placentia Bay, barytes (flesh-colored), in a large 
vein, occasionally accompanied by copper pyrites. 
Porr av Porr.—On the Isthmus, native copper, in trap. 
St. Grorce’s Bay.—Galena in limestone; at Crabb’s River, bituminous 
coal, (vein three feet in thickness), gypsum in bank of a brook, salt 
springs, 
Suoat Bay.—South of St. Johns, copper pyrites. : 
Tor Bay.—Four miles from St. Johns, a chalybeate spring, noted for its 
medicinal properties. : 
Tr ay.— Western extremity. barytes (flesh-colored), a large vein. 
Harzor Great St. Lawrence.— West side, fluor spar, galena. 
Sheffield Labratory, Yale College, Sept. 10, 1862. 
® 
Art. XXIV.—On the Correction of the Elements of the Orbit of a 
Comet ; by JAMes C. Watson, M.A., Professor of Physics 12 
the University of Michigan. 
ration and reduced to the same meridian; 4, 4, 4’’, the geocentric long 
] 
fixed epoch, which is usually taken at the beginning of the year. * 
us also denote by R, R’, R”, the distances of tke earth from the sum, @ 3 
by ©, ©’, ©”, the longitudes of the sun, for the dates of the observa 
tions respectively. third, 
The codrdinates of the first place of the earth, referred to the 
are: 
a=R’’cos ©’’—Reos ©, 
y—R" sin ©” —KRsin ©. 
If we represent by g the chord of the earth’s orbit between the places 
corresponding to the first and third observations, and by @ the go 
tude of the first place of the earth as seen from the third, we shall h# 
r==g cos G, | 
yg sinG; 
and consequently, 
R’cos(Q"’— ©) —R=geos(G - ©), ‘ 
R%sin(Q”—@) =g sin(G—O). (1) 
