ASTRONOMY: G. F. BECKER 
3 
gases at high pressures; but that gases should assume so complex a con- 
figuration as that of a spiral is difficult to understand while the con- 
tinuous spectrum is more characteristic of soHds than of gases, and Mr. 
Slipher has adduced evidence that some nebulous matter shines by re- 
flected light. The extreme tenuity and presumably low temperature 
of nebulae increase the difficulty of a purely gaseous hypothesis, which 
is further contradicted by the abundance of multinuclear nebulae. 
I infer that it is perfectly legitimate to speculate on celestial clouds 
composed of matter in more than one and perhaps in all three states. 
Provided that there is a limit to the expansion of gas, as G. W. Hill 
beheved, a gaseous spheroid may assume a figure of equihbrium and this 
is the favorite postulate among modern cosmogonists. Some of the 
more regular nebulae lend color to it; but the forms of the celestial 
clouds are as varied as those of our atmosphere and might in large part 
be similarly classified. Surely some of the elongated nebulae, resembling 
cirrus or cirro-cumulus terrestrial clouds, must eventually develop into 
more highly organized forms; or, inversely, some well-developed nebulae 
may have originated from whisps of nebulous matter, such as abound in 
the sky. 
It is not possible at present to assign a definite origin for these nebu- 
lous streamers. The hypothesis that the whole galaxy was nebulous 
at a certain epoch leads to a dilemma as was long since pointed out.^ 
In 1900 Arrhenius put forward his theory that energy is degraded in the 
solar state but raised to a higher level in the nebular state,^ and some 
such Hhird law' of thermodynamics seems logically inevitable. But 
whether or not there is a regenerative process at work among the heavenly 
bodies, there are at least inequalities of action and preferential move- 
ments (so suggestively discussed by Kapteyn) which would almost 
inevitably lead to a carding or filamentation of nebulous masses. 
It has always been impossible to suppose that nebulae were devoid of 
internal motion, but such movements were first demonstrated in 1914 
by Messrs. Buisson, Fabry, and Bourget^ for the Orion nebula. Their 
result has been confirmed by Messrs. Frost and Maney,^ who point out 
that this nebula must be considered as a mass writhing and seething in 
irregular contortions. A similar statement must be true of all nebulae. 
Consider then an elongated nebula composed of heterogeneous mat- 
ter and bounded by a surface which may be very irregular but not so 
irregular that any part of its longest principal axis falls outside of the 
mass. Such a nebula would bear some resemblance to a staff or bacu- 
lum which may be provided with knots, knobs, and excrescences. For 
the sake of brevity I will characterize such a nebula as bacular. A bacu- 
