C I0 7 ] 
and the contrary. Either limb of the Sun may be 
ufed in either o'ofervation ; but it will be moft con- 
venient in general to make the Sun appear againft 
the fky, and not againft the fea; and then the ob- 
jects appearing inverted through the telefcope, the 
Sun will appear loweft, and the horizon higheft. 
The obferved altitude is to be corrected for dip, re- 
fraction, and Sun’s femi-diameter, as ufual. 
In taking the diftance of the neareft limbs of the 
Sun and Moon, whether by the fore or back-obfer- 
vation, having firft fet the index to the diftance 
nearly, by the help of the Nautical Almanac, and 
brought the Moon to appear anywhere on or near 
the diameter of the field of view of the telefcope, 
which bifeCts the interval between the wires, give a 
fweep with the quadrant, and the Sun and Moon 
will pafs by one another j if in this motion the 
neareft limbs, at their neareft approach, juft come 
to touch one another, without lapping over, on or 
near any part of the diameter of the field of the te- 
lefcope which bife&s the interval between the wires, 
the index is rightly fet; but if the neareft limbs 
either do not come to meet, or lap over one another, 
alter the index, and repeat the obfervation till the 
neareft limbs come to touch one another properly. 
This method of obferving will be found much more 
eafy and expeditious than without the wires, fince 
in that cafe it would be neceflary to make the limbs 
touch very near the centre of the telefcope, but here 
it is only neceflary to make them do fo anywhere on 
or near the diameter of the field of the telefcope 
which bifeCts the interval between the two wires. 
P 2 The 
