424 Mr. Woodhouse's account of the 
Capella and Rigel ; the second, by the passages of Capella 
above and below the pole : and the result, equal to a deviation 
of 12".685 to the east, is in each case the same : a coincidence 
of marvellous accuracy ; and which, if the observations were 
exactly noted, we must suppose to have arisen from a fortui- 
tous balancing of the errors of the observations with those of 
the tables. 
In the method of high and low stars I suppose, which is 
almost always the case, that the clock's error is found by 
subtracting from the observed passage of the star its com- 
puted right ascension. The error may indeed be found by 
equal altitudes, should the observer possess an altitude and 
azimuth instrument of sufficient accuracy for that purpose. 
But should he not, the adjustment of the transit instrument 
by high and low stars must partake of that uncertainty to 
which we are subject in computing the true apparent right 
ascensions of stars. 
We have only to look at the catalogues of stars by different 
astronomers to be convinced of the existence of such uncer- 
tainty. If, indeed, the tabulated right ascensions differed 
only by a constant quantity, the difference of the errors of the 
clock, on which the method of high and low stars depends, 
would be the same, whether we employed Bessel's or the 
Greenwich catalogue. But it is otherwise : to instance this, 
on the 8th October, 1824, the clock going very nearly side- 
real time, the passages of Arcturus and ^ Urs. min*, were as 
follow : 
Time by Clock. 
At by N.A. 
Error. 
At by 
Schumacher. 
Error. 
Arcturus 
Q Urs. min. - 
h. m. s. 
14 7 44.56 
14 51 20.43 
s. 
40.18 
14.67 
4-38 ‘ 
5.76 
s. 
39-98 
14.95 
00 00 
