xlvili Mr. Pickering’s Eulogy on 
his most successful instances of this description. It arose from the 
following circumstance. 
In the Philosophical Transactions of the Royal Society of London, 
for the year 1824, the able mathematician just mentioned published 
a paper, in which the principles used by La Place (Book III. ch. 3, 
§ 18) in finding the equilibrium of a fluid mass were objected to as 
incomplete. Dr. Bowditch, in order to enable his readers “ to 
judge of the difficulties of the subject, and of the sufficiency of the 
commonly received laws of equilibrium,” gives a concise historical 
account of the different methods used from the time of Newton to 
the present day. After stating in his lucid manner the principles in 
question, he adds, that they “seem plain and satisfactory, and they 
were used by mathematicians during nearly a century, without any 
objection being made to thém ; and there was no doubt, in the mind 
of any one, that they comprised all the conditions necessary to the 
equilibrium of a fluid.” 
But in the paper abovementioned Mr. Ivory proposes another 
condition ; which need not, however, be here stated. 
This led to a reéxamination of the subject ; and among the 
numerous opponents of Mr. Ivory’s opinion was the celebrated 
French mathematician, M. Poisson; who, as Dr. Bowditch observes, 
points out several examples, in which Mr. Ivory’s new principle, 
carried to its full extent, would lead to an erroneous result. To 
these examples Dr. Bowditch adds only one of his own (above 
alluded to), which he calls “an extremely simple case”; but that 
simple case decides the fate of the proposed rule. 
In a subsequent part of this second volume (Book III. ch. 5, 
§ 42) Dr. Bowditch notices an error in the computation of the 
figure of the earth, as deduced from the observed lengths of a pen- 
dulum in different latitudes ; and he points out here, as he had 
done many years before in the Academy’s Memoirs, the probable 
