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APPENDIX B.

AZIMUTHS OF ALINEMENTS ON THE MAPS AND PLANS.

AZIMUTHS.AZIMUTHS.
No.1Angle of110½° or290½° No.31Angle of0° or180°
,, 2,,129° ,,309° ,,32,,1° ,,181°
,, 3,,138½° ,,318½° ,,33,,70° ,,250°
,, 4,,169° ,, 319°349° (checked on map) ,,34,,61° ,,241°
,, 5,,27° ,,207° ,,35,,72° ,,252°
,, 6,,38° ,,218° ,,36,,127° ,,307°
,, 7,,52° ,,232° ,,37,,61° ,,241°
,, 8,,62° ,,242° ,,38,,51° ,,231°
,, 9,,52° ,,232° ,,39,,35° ,,215°
,,10,,68½° ,,248½° ,,40,,42° ,,222°
,,11,,67° ,,247° ,,41,,71° ,,251°
,,12,,88° ,,268° ,,42,,156° ,,336°
,,13,,89° ,,269° ,,43,,165° ,,345°
,,14,,90° ,,270° ,,44,,64° ,,244°
,,15,,89° ,,269° ,,45,,57° ,,237°
,,16,,156½° ,,336½° ,,46,,66° ,,246°
,,17,,111° ,,291° ,,47,,101° ,,281°
,,18,,179° ,,359° ,,48,,43° ,, 233°223° (checked on map)
,,19,,72° ,,252° ,,49,,109° ,,289°
,,20,,66° ,,246° ,,50,,178° ,,358°
,,21,,80½° ,,260½° ,,51,,71° ,,251°
,,22,,90° ,,270° ,,52,,142° ,,322°
,,23,,122° ,,302° ,,53,,60° ,,240°
,,24,,124° ,,304° ,,54,,93° ,,273°
,,25,,0° ,,180° ,,55,,89° ,,269°
,,26,,179° ,,359° ,,56,,155° ,,335°
,,27,,1° ,,181° ,,57,,165° ,,345°
,,28,,81° ,,261° ,,58,,72° ,,252°
,,29,,52° ,,232° ,,59,,78° ,,258°
,,30,,91½° ,,271½° ,,60,,81° ,,261°
,,61,,56° ,,236°

I do not attempt to give the right astronomical definition of an azimuth. But for its application to this investigation it is the angle which the alinement makes (counting clock-wise) to true north.

{53} Herein comes a difficulty. An alinement (as say No. 22), can be looked at from both ends, and looking eastward, that is to sunrise, this one is 90°; while looking westward it is 270°. If actually sighting to sunrise or sunset, as observers have done from ancient stones, &c., you know which of the two angles you are taking, and only one figure is given as the azimuth. But as regards this book I only know the resulting line, and have no idea (it might be found with local observation) in which direction the track or line was first sighted. No. 22, if sighted in one direction, might be to sunrise at the Equinox, at an horizon elevation of about 1°. But it might also be (as can be noted in Appendix A.) sunset at the Equinox at about the same elevation. Admiral Somerville, in drawing up his table, knew of which these directions he speaks, but in the subjoined table, drawn up as an aid to consulting this, I do not know, and am obliged to give both angles, one of course being always half a circle (180°) more than the first.

These angles were taken from a meridional line with a six-inch circular protractor, and are (I trust) within half a degree (or less) of accuracy.

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