222 
the globe being solid throughout, and fluid respectively; and if 
w=n sin pt, w' will be =n’ sin pt — m’' cos pt, where m’ will be 
at least »~.th of n, .. n'=n nearly, unless w’ the coefficient of 
fluid friction of the globe’s interior be at least 150,000,000 
times that of water; and for forces going their Ae in 20 
years yu’, in order that m’ may be not more than =~, must be at 
= 
27000 
20 
value of w' in water. The application of these facts to the 
phenomena of Precession and Nutation is obvious, and points 
to a condition of the interior of the globe which is inconsistent 
least x this great value, or at least 200,000,000,000 the 
with all notions of fluidity; since a deviation, not merely from 
the value, but from the force of w to the extent shewn above, 
would not escape observation and detection. 
Mr Rohrs observed in conclusion, that he did not know how 
far, or if at all, he had been anticipated by other persons in the 
solution of these problems; as the problems present no diffi- 
culties of analysis, 1t was likely he had been, but he was not 
aware of that fact—his work was entirely his own. He had 
heard, however, that since his paper had been in the hands of 
the Society, that is, within the last year or more, Mr Stone, of 
Greenwich, had announced that tidal retardation was practi- 
cally insensible in amount. | 
Professor STOKES thought that it would not be safe to 
assume (as had been done) the value of the constant which had 
been determined by himself, for in investigating that case the 
motion in the fluid had been supposed very slow, so that no 
eddies were formed, and fluid friction only acted. But in the 
problem of the tides, as the bed of the ocean would generally 
be rough, the formation of eddies would be an important ele- 
ment in the matter, and thus the resistance might be much 
greater than in the case contemplated above. 
Mr O. FISHER mentioned that Archdeacon Pratt had veplige 
