48 Lord Brougham’s Address on the Inauguration of a 
these characteristics of high and original genius we may be per | 
mitted to compare the career of those great men. But Co um: 
bus did not invent the mariner’s compass as Newton did the ~ 
instrument which guided his course and enabled him to make — 
his discoveries, and his successors to extend them by closely fol- ’ 
having solved an isoperimetrical problem (finding the line whose — 
revolution forms the solid of least resistance,) shows clearly that 
he must have made the coordinates of the generating curve vary, — 
and his construction agrees exactly with the equation given by — 
that calculus. That he must have tried the process of integra- 
ting by parts in attempting to generalize the inverse problem of 
central forces before he had recourse to the geometrical approx! _ 
mation which he has given, and also when he sought the means — 
of ascertaining the comet's path, which he has termed by far the — 
most difficult of problems, is eminently probable, when we con- 
sider how naturally that method flows from the ordinary process — 
for differentiating compound quantities, by supposing each vatl — 
able in succession constant; in short, differentiating by parts. 
As to the calculus of variations having substantially been 
known to him no doubt can be entertained. Again: in estima 
ion. One of these phenomena, wholly unsuspected before 
the discovery of the general law, is the alternate movement to 
and fro of the earth’s axis, in consequence of the solar (and als0_ 
of the lunar) attraction combined with the earth’s motion. This 
