60 
science demanded more than a simple record of the transits, 
after the errors of the instrument had been rectified. For 
information and counsel on this, as well as other important 
points, I most respectfully tender my thanks to Rev. Rich- 
ard Sheepshanks, and to S. C. Walker, Esq., gentlemen 
whose devotion to and labors in the cause of astronomy have 
established for them most enviable fame. 
“ Limited to the Nautical Almanac and the catalogues con- 
tained in the volumes mentioned, for observable objects, MY 
attention was early arrested by discrepancies between the 
clock errors resulting from standard stars and some of those 
comprised in the list of moon-culminations ; discrepancies 
amounting in several cases to more than two seconds of time, 
which, being confirmed by the observations of consecutive 
nights, were consequently altogether beyond the limits 
probable errors. Receiving about this time, through the 
kindness of Mr. William Simms, a copy of that vade mecum 
of astronomers, ‘The Catalogue of the Royal Astronomical 
Society,’ it occurred to me, that, whilst carrying out the © 
jects of the exploring expedition, the mites which I could 
add to the data for more correctly locating ‘the landmarks 
of the universe’ would not be entirely unworthy of collection 5 
and, with this object in view, I determined henceforward to 
increase the number of stars to be nightly observed, so a8 ss 
embrace one in each three and a half to four minutes be 
tween the times of transit of the first and last moon-culminat- 
ing star, — the interval fixed on being the time ordinarily 
occupied by the transit of one star over all the wires, and 
setting the finder for its successor. This was all I could 
hope to accomplish with the, means in my power, unless 
_ careful estimations of the apparent magnitudes of each star 
observed should enable me to detect, at the termination of 
_ the series, variations in their brightness, or to confirm the 
degree of lustre already assigned to them. 
