68 Li Con CLANS ETN 
the test here applied the question of nebular density does not 
enter, and certain assumptions that might be made to meet the 
previous discrepancies are here checked. 
Just previous to the hypothetical separation of the Jovian 
ring from the solar nebula the moment of momentum of the 
latter, reckoned from the present momenta of its derivatives, was 
14.1816, if the sun be regarded as homogeneous, or 13.947, if 
the sun’s density followed Laplace’s law which is probably much 
nearer the truth. Of this, Jupiter now has 13.469. Neglecting 
for the present subsequent transfers of momentum, it follows that 
when the Jovian ring separated it carried away 13.469 / 14.182 or 
about 95 per cent. (94.97 per cent.) of the total moment of momen- 
tum of the nebula (or 96.57 per cent. on the more probable basis). 
Now the mass of Jupiter’s ring was 1 / 1049 of the parent nebula, or 
less than one tenth of 1 percent. It thus appears that the unquali- 
fied Laplacian hypothesis involves the implicit assertion that in 
the formation of the Jovian ring less than one thousandth of the 
mass carried away 95 per cent. of the moment of momentum. Is 
this possible in a spheroid of gaseous or quasi-gaseous material 
in convective equilibrium? One nineteen-thousandth more of 
the mass thrown off with an equal proportion of rotational 
momentum would have exhausted the supply. Apparently the 
minor planets had a narrow escape from not being at all. 
Similar but not uniform disparities appear in a comparison 
of the masses and momenta of the other planetary rings with 
their parent nebule. In such a comparison also the great dis- 
parities in the planetary masses become conspicuous. 
The mass of the Neptunian ring was about five thousandths 
of I per cent. of its nebula and by hypothesis it carried away 
about 8 per cent. of the moment of momentum of the nebula. 
The mass of the Uranian ring was four and a half thousandths 
Oi Woe CeMu, Ou tes nebula. It hypothetically carried away 6 
per cent. of the nebular moment of momentum. 
The mass of the Saturnian ring was less than a third of a 
hundredth of 1 per cent. of its nebula and yet it carried away 27 
per cent. of the nebular moment of momentum. 
