in Reply to a. Paper In the Quarterly Journal. SI 
be feared, will be found equal to 0,000044; and as this error 
may be either in excess or defect, it would be unsafe to hazard a 
bet, that the length of the seconds pendulum, in the latitude 
inch. 
of London, is greater than S9,1S9006, which differs from the 
length of the said pendulum, as^determined by Mr Whitehurst, 
by only 0,000154 parts of an inch in defect. 
It is beneath the dignity of philosophical discussion even to 
notice the observation of Z, respecting an object being seen . 
through a telescope, when it is not in the field of view ; because 
it consists in a mere sophism, which logicians denominate “ ig~ 
noratio elenchij or mistake of the question, that is, v/hen some- 
thing else is proved which has no necessary connection with the 
thing inquired into, and consequently gives no determination to 
the inquiry, although it may seem, at first sight, to determine 
the question. 
I may, therefore, repeat the question, Why cannot the 
disappearance of the disk, (or, in other words, why cannot the 
instant when the disk disappears,) be noted to a quarter of a 
second, as readily as to an entire second Biot has noted the 
periods of coincidence to a fraction of a denary second, and, in 
my opinion, no sufficient reason can be assigned why Captain 
Kater could not have done so likewise. 
I shall conclude 'my remarks by observing, that the editor of 
the Quarterly Journal of Science has thought proper, in two 
places of the Index to No. 16., to apply to my remarks on Cap- 
tain Kater’s experiments, the opprobrious epithet illiheral ; but 
with what degree of justice or propriety he has ventured on 
such an ummrrantahle interference, with an individual who has 
given no just ground whatever for reproach, I most cheerfully 
submit to the decision of the public, only requesting, that it may 
be kept in view, that the question principally relates to very 
minute quantities; such, for example, as the 10,000th part of 
an inch, or to such a degree of accuracy as had not hitherto 
been attained ; for the length of the seconds pendulum had been 
at least virtually determined to about the 10,00Cth part of an 
inch long before Captain Kater'^s attention was directed to the sub- 
ject ; and it was even a still greater degree of exactness, as well 
