Mr. Wood house on the derangements, &c. 145 
transit instrument, are very different from mine. They differ 
not in degree, but altogether. According to Mr. South, his 
transit instrument is alike steady and faithful to its duties, 
whether it be in shade or be exposed to the noon day sun. His 
instrument, in some respects, that is in the putting together 
of the tubes composing the telescope and axis, is different 
from mine ; but it is furnished with similar braces ; and that 
these should in no wise derange the instrument to which they 
are fixed, whilst similar ones, under certain circumstances, 
so greatly deranged mine, was a fact that considerably sur- 
prised me. Amongst other considerations a natural sugges- 
tion arose to my mind, whether I had not, from want of 
sufficient experience, or from negligence, committed some 
great mistake. To resolve this doubt I instituted the follow- 
ing experiments. 
By a great number of previous observations the polar 
intervals of the wires of my transit ( the perforated axis being 
towards the west) are 
Upper culmination. Lower culmination, 
m. s. m. s. 
10 39.4 
10 39.2 
36.2 
32.5 
28.7 
38.2 
38.2 
28.7 
32.5 
36.2 
39 - 2 
39-4 
Hence the numbers to be added to the observed transits at 
the 1st, 2d, 3d, &c. wires, in order to compute the transits at 
the succeeding wires, will be represented by the two follow- 
ing tables. 
MDCCCXXVII. 
U 
