EDITORIAL 275 
hypothesis does not seem well fitted to the sun itself in this late 
stage of its history. The alternative conjecture that the attenuated 
form of matter is developed in the sun by the extraordinary agen- 
cies operative there must obviously be entertained until disproved, 
and the recent investigations of J. J. Thompson and others with 
reference to the extremely attenuated ionization of terrestrial 
gases under certain conditions render such a hypothesis less 
highly improbable than it would have seemed under the domi- 
nance of the inherited doctrine of the indivisibility of the atom. 
A speculation which involves the notion of the divisibility of 
the atom involves also that of the divisibility of the internal 
energies of the atom and their possible transformation into 
radiant energy,and hence a possible source of heat of unknown 
and, at present, quite incalculable amount. 
So too, a speculation which assumes that the corona is 
radiated matter involves also the conception of loss of sun’s 
substance if the velocity of radiation be as high as that attributed 
to the conjectural matter of comets’ tails; and if this loss of 
matter in the course of great secular periods becomes appreciable, 
it may require a reconsideration of the data upon which estimates 
of the sun’s heat are based and also of a revised consideration 
of the former distances of the planets. 
Now such an attenuated chain of hypotheses, each dependent 
on an antecedent hypothesis of uncertain verity, may be alto- 
gether too unsubstantial to have any appreciable value of the 
positive sort, other than as the antecedent of investigation, but it 
may have the negative virtue of helping to keep open the question 
of the sum total of the sources of the sun’s heat and its possible 
duration in the past and the future. And so possibly may also the 
logical sequences of the alternative coronal hypotheses. The 
Helmholtzian theory assigns a source of heat of such competency 
that it cannot be proved not to be the sole essential cause by any 
measurements of the sun that can be made now, or probably in 
the near future, and hence it satisfies the immediate demands of 
astronomical science, however inadequate it may be to meet 
the natural interpretations of geological and biological data; 
