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been shown to depend upon the phase of the
sun-spot period. During the sun-spot maxi-
mum the corona seems most developed over
the spot-zones–i.e., neither at the equator
nor the poles. The four great sheaves of
light give it a square appearance, and are
made up of rays or plumes, delicate like the
petals of a flower. During a minimum the
nebulous ring seems to be made of tufts of
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