374 A. W. Wright—Polariscopic Observations of Comet c, 1881. 
45°, and changes very plage in the region corresponding to 
the incidences given in the ta 
me the case of comet 0}, the “Ant angle of incidence was 
arly 60°, and as this diminished the polarization was seen 
nS "icin likewise; but it happened that at the times of 
widest incidence the comet was near its perihelion. A maxt- 
mum occurring with an incident angle as large as 60° would 
hardly be looked a if the — ‘of polarization depended 
upon this angle alon f the reflecting material were wholly 
gaseous the greatest puwtean should be found at 45° inci- 
dence; but though a tendency toward a secondary maximum 
at this angle may be suspected, the observations are not 
sufficient to definitely establish its existence. The changes 
actually observed are with difficu'ty reconciled with the sup- 
position that the reflection took place rom gaseous substance 
the sun, and while it remained near the perihelion, some 
form of volatizable matter may have been eliminated by the 
increasing temperature, and that the subsequent condensation 
of this gave rise to the presence of minute liquid or solid parti- 
cles in the gaseous matter first thrown off. The varying pro- 
aed probably that of the tail, aes out light of itself, The 
action just described must alter the relation of the emitted to 
the reflected debe and this would have its effect upon the 
degree of polarization. 
The earlier observations of comet 6, made soon after its peri- 
helion passage, show occasional irregularities, and the variations 
are in some cases decidedly greater than the ordinary errors of 
pig ls The sky at the time appeared very clear, and the 
eric conditions were probably not the sole cause of the 
factantions It seems almost certain that at this period of 
reat activity the polarization was subject to considerable 
kets of an irregular character and comparatively brief 
duratio 
Yale Callies October 15, 1881, 
