days comparisons which we made, assured us that the watch had
not materially, if at all, altered her rate of going; and gave us the
same longitude, within a very few seconds, that was obtained by finding
the time from observations of the sun's altitude from the horizon of the
sea. The watch, from a mean of these observations, on the 1st, 2d, and
3d of August, made the longitude 16 deg. 31' W.; and, in like manner, the
latitude was found to be 28 deg. 30' 11" N.

Mr Varila informed us, that the true longitude was 18 deg. 35' 30", from
Paris, which is only 16 deg. 16' 30" from Greenwich; less than what our
watch gave by 14' 30". But, far from looking upon this as an error in
the watch, I rather think it a confirmation of its having gone well; and
that the longitude by it may be nearer the truth than any other. It is
farther confirmed by the lunar observations that we made in the road,
which gave 16 deg. 37' 10". Those made before we arrived, and reduced to the
road by the watch, gave 16 deg. 33' 30"; and those made after we left it,
and reduced back in the same manner, gave 16 deg. 28'. The mean of the three
is 16 deg. 30' 40".

To reduce these several longitudes, and the latitude, to the Pic of
Teneriffe, one of the most noted points of land with geographers, (to
obtain the true situation of which, I have entered into this particular
discussion,) I had recourse to the bearing, and a few hours of the
ship's run after leaving Santa Cruz road; and found it to be 12' 11" S.
of the road, and 29' 30" of longitude W. of it. As the base, which
helped to determine this, was partly estimated, it is liable to some
error; but I think I cannot be much mistaken. Dr Maskelyne, in his
_British Mariner's Guide_, places the Pic in the latitude of 28 deg. 12'
54". This, with the bearing from the road, will give the difference of
longitude 43', which considerably exceeds the distance they reckon the
Pic to be from Santa Cruz. I made the latitude of the Pic to be 28 deg. 18'
N. Upon that supposition, its longitude will be as follows:

{The time-keeper, 17 deg. 0' 30" }
By {Lunar observations, 16 deg. 30' 20"} W.
{Mr Varila, 16 deg. 46' 0" }

But if the latitude of it is 28 deg. 12' 54", as in the _British Mariner's
Guide_, its longitude will be 13 deg. 30' more westerly.

The variation, when we were at anchor in the road, by the mean of all
our compasses, was found to be 14 deg. 41' 20" W. The dip of the N.