20 REPORT—1846. 
everything is supposed to be perfectly smooth, the ratio ought to be inde- 
pendent of the magnitude of the sphere. In the imperfect theory of friction 
in which the friction of the fluid on the sphere is taken into account, while 
the equal and opposite friction of the sphere on the fluid is neglected, it is 
shown that the are of oscillation is diminished, while the time of oscillation 
is sensibly the same as before. But when the tangential action of the sphere 
on the fluid, and the internal friction of the duid itself are considered, it is 
clear that one consequence will be, to speak in a general way, that a portion 
of the fluid will be dragged along with the sphere. Thus the correction for 
the inertia of the fluid will be increased, since the same moving force has now 
to overcome the inertia of the fluid dragged along with the sphere, and not 
only, as in the former case, the inertia of the sphere itself, and of the fluid 
pushed away from before it, and drawn in behind it. Moreover the addi- 
tional correction for inertia must depend, speaking approximately, on the 
surface of the sphere, whereas the first correction depended on its volume, 
and thus the effect of friction in altering the time of oscillation will be more 
conspicuous in the case of small, than in the case of large spheres, other cir- 
cumstances being the same. The correction for inertia, when friction is 
taken into account, will not, however, depend solely on the magnitude of the 
sphere, but also on the time of oscillation. With a given sphere it will be 
greater for long, than for short oscillations. 
Sixth Report of a Committee, consisting of H. EK. Srrickuanp, Esq., 
Prof. DauBeny, Prof. HeEnstow, and Prof. Linpury, appointed 
to continue their Experiments on the Vitality of Seeds. 
THESE experiments have again been repeated upon 48 kinds of seeds ga- 
thered in 1843, as well as upon 26 kinds of new seeds added to the general 
collection in 1845. 
Many kinds‘of old seeds, of various dates from 1812 to 1845 inclusive, 
consisting of 151 packets, have been contributed by Miss Molesworth. These 
were for the most part in small quantities, and were sown only at Oxford, on 
a slight hot-bed. 
A small quantity of soil from the bed of a freshwater lake of the tertiary 
period, at Mundesley, Norfolk, containing scales of fish, elytra of beetles, 
seeds of Ceratophyllum and other plants from Sir W. C. Trevelyan, was sub- 
jected to three tests; viz. one-third part was placed in a shallow pan, and 
kept moist with distilled water; the second portion was kept well-saturated 
with the same; and the third portion, also in a shallow pan, under about 
one inch of distilled water. The whole was kept under a glass case to pre- 
vent the chance of seeds, &c. being deposited in it. No vegetation appeared 
in either case. 
It may be well to remark, that the seeds have been sown under different 
circumstances, and have received different treatment at each of the three 
places they have been experimented upon. At Oxford, as in previous years, - 
a selection was made from the whole quantity to be sown, of such as usually 
require the assistance of heat to enable them to germinate ; these were sown 
in pots and placed in slight heat, and the remainder were sown on a small 
bed made in a cold frame, and, with the exception of two or three waterings, 
left to nature. 
At Hitcham they were all sown in a border carefully prepared for them, 
and afterwards left to nature. 
