HI. A. Newton— Origin of Comets. 179 
inexplicable. The same is true for the downward turn of the 
curve near A when the comets of short period are thrown out, 
wholly, or in part. The effect of perturbation should be to 
push the area forward towards B. 
But if the comets come from matter somewhat nearer to the 
therefore, whose inclinations are increased, would return more 
uently and so be more likely to apres in our list, while 
some of those whose inclinations are diminished would go off 
altogether. But the perturbations would not easily remove the 
excess of area from near A in the figure. We therefore con- 
t seems very improbable that iron masses whose like in the 
earth is found only in the igneous trap rocks, especially in the 
Greenland traps, should have become consolidated in the cold 
iTagments are records of an interesting early history. To 
decipher the legends belongs rather to the mineralogist and 
the physicist than to the astronomer. My effort bas been to 
