LONGEVITY. ; 219 
it betakes itself to a rock or rough stone, and rubs 
its beak till the overgrown part is ground down into 
proper proportion. 
Albertus Magnus gives a still more ingenious pro- 
cess of renewal, not, however, of his own inven- 
tion, but quoted from Jorachus and Andelinus, whose 
works, we presume, are now lost. “They say,” 
reports Albertus, “that an old eagle at the period 
the young ones are fledged, as soon as she has dis- 
covered a clear and copious spring, flies directly 
upward, even to the third region of the air, which 
we term the region of meteors, and when she feels 
warm, so as to be almost burning, suddenly dash- 
ing down and keeping her wings drawn back, she 
plunges into the cold water, which, by the astringing 
of the external cold, increases the internal heat. 
She then rises from the water, flies to her nest, and 
nestling under the wings of her warm young ones, 
melts into perspiration, and thence with her old 
feathers she puts off her old age, and is clothed 
afresh; but while she undergoes this renovation, 
she makes prey of her young for food. But I can 
only,” he adds, “ consider this as a miraculous oc- 
currence, since in two eagles which I kept I ob- 
served no changes of this sort; for they were tame 
and docile, and moulted in the same manner as 
other birds of prey.” 
It is very obvious that all these are mere fancies, 
and farther, that there are few or no data by which 
to determine the age of wild birds. We have, in- 
deed, observed among hkouse-sparrows individual 
cockbirds, in which the black markings were inter- 
mixed with white feathers: but whether this was 
the hoariness of age, or merely an accidental va- 
riety of colour, we had no means of ascertaining. 
It has been long decided that the grayheaded crow 
is not an old carrion crow grown hoary with age as 
is popularly believed; but a different species (Cor- 
VUS COTNIZ). 
