1881.] and its Effect on Astronomical Observations. 513 
annually, and we can obtain from these curves even more 
accurate results than can be obtained by years of wearying 
observation at hundreds of observatories. 
That which makes the problem at first sight somewhat 
complicated is, that whilst this annual rotation displaces the 
poles of diurnal rotation, the same annual rotation will not 
displace the plane of the Equator ; consequently the plane 
of the Equinoctial would still cut the Heavens in the same 
great circle, no matter whether one rotation occurred round 
the poles of the Heavens or round two other poles distant 
20" from them, and on the same meridian of right as- 
cension. 
That the centre of gravity of the Earth does not and 
cannot coincide with the centre of the Earth is a problem 
which has never yet been investigated by astronomers or 
geometricians. That so slight a variation of the position of 
this centre of gravity as 2100 feet could produce such sin- 
gular results as those demonstrated in this paper has also 
escaped observation. That two curves could be constructed 
by aid of which the changes in polar distance of stars near 
the pole could be measured, and the changes in right ascen- 
sion of every star in both hemispheres demonstrated, is 
certainly a faCt of some importance. 
To prevent any enquiry, by suppressing a paper on this 
subject, is a proceeding scarcely consistent with a love of 
truth, or a desire for the advancement of true science. 
The changes found in the zenith distance of stars were 
first discovered by Bradley in 1725 : he states, in his paper 
in the “ Philosophical Transactions ” (1728), that he at first 
thought that the changes might be accounted for by Solar 
Nutation, but having failed to find any movement of the Earth 
which could account for the observed fads , he attributed the 
changes to a combination of the velocity of light and of the 
Earth’s movements in space, and called the cause “Aberra- 
tion.” With the permission of the Editor of this Journal I 
will shortly give a paper calling attention to this theory of 
Aberration, and comparing its value as a supposed cause 
with the faCts resulting from the centre of gravity of the 
Earth not coinciding with the Earth’s centre. 
