62 
REPORT —1854. 
been at infinitely greater distances from one another in space than they are now. 
He remarked that the nebular theop', as ordinarily stated, assuming as it does a 
previously gaseous state of matter, is not only untrue, but the reverse of the truth, 
according to the views now brought forward, since these show evaporation as a 
necessary consequence of heat generated by collisions and friction, and the genera! 
past and present tendency of matter is seen to be the conglomeration of solids 
and liquids accompanied by a gradual increase of the quantity of gaseous fluid 
occupying space. 
Prof. Helmholtz, in a most interesting popular lecture on transformations of 
natural lorces, delivered on the 7th of February last at Konigsberg, has estimated 
that, if the particles at present constituting the sun’s mass have been drawn 
together by mutual gravitation, from a state of infinite diffusion, as supposed in the 
nebular theory, not however a gaseous state, as ordinarily supposed, but a state in 
w nch the particles exercise no mutual action except that of gravitation, the whole 
neat generated must have amounted to about 28,000,000 thermal units Centigrade 
per pound of t he sun s mass. This estimate would not, as the author of the present 
paper shows, require any change, whether we assume, as the antecedent condition of 
u so ar mass, a state of infinite diffusion, or a state of aggregation in solid masses 
any (intensions small compared with his present dimensions, and separated from 
”. e ^ no e *". al comparatively great distances ; provided always there has been no 
f linn ''ll m<> V 01 , 1 aui0D S them except what is generated bv mutual gravitation. If, 
author' 0 6 tn J lSS ol tbe sun bas grown by the process which, according to the 
• S „ ,leor >' °* s ohu' heat (certain as regards a part, whether or not it may be 
aujrmnnti ° acc ° unt ,or the whole of the radiation of solar heat), we know to be 
at present, there must have been generated, in the whole process of 
nboiit 20 nnn nnn*' <,uailt,t y °f heat stated above ; a quantity which amounts to 
aoIr SpTr tunes ns much as is at present radiated off in one year. Toe 
off’ imniedintrlv on 8 | ? r believing that this heat must have been nearly all radiated 
the con atom pi'nf-o i Cin ® S enera tcd, and that enough of it has not been retained in 
U drawn ° t0 be the store from wtfch the heat at present radiated 
in the ra ^' at ' on is supplied chiefly from a store of heat contained 
meteors which linvo'rnTi 1,3 ^^ t ! ler . e or generated mechanically by the impact ot 
improbable. ai en ln during remote periods of past time, appears very 
plying heat * n all probability be some agency continually sop - 
»u"n; and that nrr P i!f?* att f , le loss constantly experienced by radiation from the 
the mechanical J as tae au thor has shown elsewhere, can be no other than 
sun to rest on bis surface'”asses coming from a state of very rapid motion round Utf 
rest and at great'tlisfnn^^ 0 ? a s -' stern of solid bodies, large and small, initially 3 ] 
by the resistance their s .f rotn one another, may, by their mutual gravitations,aa 
rated from them bvtbo h° “ lu . st experience in the gaseous atmosphere, evapo* 
a state of motion heat nn!i °r t , le ‘ r collisions after a vast period of time, come 
system and the stars Th 0 * an alogous to the present condition of our so* 
different systems startino- f ° ri ® iri rotatory motion is explained by showing 
frnrj rotatory motions witl° n \ re8t influence one another so as to acquire con- 
by the whole. Any svslen °. &n ' a SS re gate of rotatory momentum being acquire] 
mass, after having thus -° r , grou P beginning to concentrate round one princ'P" 
it, in a certain sta"-e of n ,il irC( a m °nientum of rotatory motion, will acquire m 
° ncement, just such approximately circular motions 
be the ene^gy^f g^Iihadon 2fcl?- ,,0t * as the ne bular theory has led some to suppose it«?' 
since without Increased pressure any con flnued condensation of the sun’s present >«*• 
place; and the heat emitted in r’ nn ' S ° nIy by cooling that any condensation can be ts'•'? 
°n tn<* specific heat of tli P e ^ uence of condensation by cooling, would depend tnt. 
and pressure, and might ff n - e mass in its actual circumstances of tempera 
temperature and pressures) be urn., " e know of the properties of matter at such '. 
the work done by gravity on the than » equal to, or less than the thennal equivakn 
7 lue contracting body. 
