e facts alone ought to have awakened the attention of Captain
Sabine, and of those who examined and officially pronounced on the
merits of his observations; for, supposing the skill of the observers
equal, it seems a necessary consequence that "the performance of the
six-inch circle is" not merely "fully equal to that of circles of larger
dimensions," but that it is decidedly SUPERIOR to one of sixteen inches
in diameter.

This opinion did indeed gain ground for a time; but, fortunately for
astronomy, long after these observations were made, published, and
rewarded, Captain Kater, having borrowed the same instrument, discovered
that the divisions of its level, which Captain Sabine had considered to
be equal to one second each, were, in fact, more nearly equal to eleven
seconds, each one being 10.9sec. This circumstance rendered necessary
a recalculation of all the observations made with that instrument: a
re-calculation which I am not aware Captain Sabine has ever thought it
necessary to publish. [Above two hundred sets of observations with this
instrument are given in the work alluded to. It can never be esteemed
satisfactory merely to state the mean results of the corrections arising
from this error: for the confidence to be attached to that mean will
depend on the nature of the deviations from it.]

This is the more to be regretted, as it bears upon a point of
considerable importance to navigation; and if it should have caused
any alteration in his opinion as to the comparative merits of great and
small instruments, it might have been expected from a gentleman, who was
expressly directed by the Board of Longitude, to try the question with
an instrument constructed for that especial purpose.

Finding that this has not been done by the person best qualified for
the task, perhaps a few remarks from one who has no pretensions to
familiarity with the instrument, may tend towards elucidating this
interesting question.

The following table gives the latitudes as corrected for the error of
level:

Station. Star Latitude Latitude Diffe-
by Capt. corrected for rence
Sabine error of level.

deg.min.sec. deg.min.sec. sec.

Sierra Leone Sirius 8 29 27.9 8 29 34.7 6.8

Ascension Alph.Centuri 7 55 46.7 7 55 40.1 6.6

Bahia