Nebular Thcory.^Mistocklcs. 319 
the sinallcr planets than to that of the larger, appears to be 
the sole reason for the inclination of the orbits of the minor 
planets between Mars and Jupiter of from 8° to 30" to the 
ecliptic. The same condition is, therefore, the cause which 
prevents the reciprocal attraction of the Sun and the large 
planets from keeping the minor planets in orbits parallel to 
the orbits of the large planets. 
In view of this, it is also evident, that Saturn's inclination 
of 23/^° to the ecliptic is due to his large appendix of rings, 
on account of whicli he meets a much greater resistance in 
proportion to his mass than, for instance, Jupiter. 
In conclusion a few remarks may be added as to the in- 
clination of the orbits of the moons O'f other planets, as, for 
instance, in the case of I'ranus. This question I intend to 
deal with separately from the one discussed above. 
I will say beforehand, however, that by a thorough exam- 
ination, we shall tind at least two forces, aside from that of 
gravity, acting upon the satellites. We shall also find that 
one of these forces is at work most strongly in the outer 
region of the solar system, and affects the satellites of the 
remotest planets the most and determines the inclination of 
their orbits, while the other one, as shown above, acts strong- 
est on iDOth the moons and planets which are nearest to the 
Sun. For this reason it would be an error to assume, as some 
might be apt to do, that the inclination of the orbits of all the 
satellites to the orbits' of their respective planets is, in all 
cases, due to one and the same cause. 
(To he Contimied.) 
EDITORl.VL COMMEXT. 
The Stoxe Reefs of i'.it.vziL. 
Tlie Stone Rcefss of Brazil; Their geological and geographical relations, 
li'ith a chapter on the coral reefs. John C. Branner; pp. 285, 99 
plates. Bulletin of the Museum of Comparative Zoology, vol. 44, 
Cambridge, 1904. 
This volume is the result of labor that has been in hand 
for about 25 years during which Dr. Branner, in getting the 
information upon which his conclusions are based, has gath- 
ered probably the largest library extant on Brazilian and 
