356 
Proceedings of the Royal Society 
throughout the civilized world ; for after all their efforts during the 
last fifty years, and notwithstanding the stupendously large sur- 
veys they have been carrying on, at an enormous expense to the 
nations concerned, in order to ascertain the size and shape of the 
earth, — the Proceedings ’ author declares, that the length of the polar 
axis thereof, “ is still an unknown and undetermined linear 
“ quantity.” 
Yet, if we take even twice Captain Clarke’s two limits, already 
given, — the difference of their mean from either one or other, 
amounts to less than io~^~oo-th part of the whole axial length : — 
a proportional quantity, which, on a foot-rule, would be equal to 
a lengthening or a shortening of it by much less than the 
breadth of a hair of the finer human order. And inasmuch as 
rules are sold in good opticians’ shops as foot rules, or as being of 
the known length of a foot, though they may differ from each 
other in length by more than ten whole hairbreadths, — why, it 
is plain that the length of the axis of the earth is to be considered, 
even as compared with some modern measuring rules, to be remark- 
ably well determined and known. The statement of the Proceed- 
ings author is therefore an unfounded slur on the work and re- 
putation of the best astronomers, geodesists, and surveyors of many 
countries, both in the present and past generations ; men who 
have deserved exceedingly well, both of the scientific and general 
public, throughout the whole civilized world. 
Accusation Fourth. 
4. That in the same Proceedings' paper, where the length of the 
earth’s axis has been declared by its author to be “ an unknown 
“ and undetermined linear quantity,” — there should be the follow- 
ing sentence : — “ The engineers and mathematicians of different 
“ countries have repeatedly measured a meridian arc of a degree of 
“ sixty miles, in order to use it as a standard for linear divisions. 
“ As part of their standard, they measure off sixty miles of the ir- 
“ regular earth-surface of a kingdom with almost perfect mathe- 
“ matical exactitude,” — may seem extraordinary. 
Extraordinary in the first place — because, though a project has 
been started from time to time, of using some special round and 
even subdivision of the length of a sexagesimal degree of the meri- 
