The construction of the wonderful canon of logarithms

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In
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Notes on Trigonometrical Propositions. 77
logarithm add, as before, 693147, and the sum, that is
the number remaining since the sines are contrary, will
be 638826, half of which, 319413, is the logarithm of
46° 36' o". The arc of the given logarithm is therefore
93° 1 2' o", the versed sine of which is 105582 16, and since
this is greater than radius it has a negative logarithm,
namely —54321.
Demonstration.
, j-versed sine of arc] ,
X c ") cont. X a "j cont. ix c, sine of 30° o' \ cont.
c g > pro- a e > pro^ c g, sine of ^ arc c d > proc
h ) port. a f )
port. c b, double of line c h ) port.
.Letter on I observed that the sixth proposition might be
proved in an exactly similar way.
Of the spherical triangle A B D ]
finding the base we may pursue another method^
namely:—
Add the logarithm of the versed sine of the given angle to the
logarithms of the given sides, and the sum will be the logarithm of
the difference between the versed sine of the difference of the sides
and the versed sine of th£ base required. This difference being
consequently known, add to it the versed sine of the difference of the
sidesy and the sum. will be the versed sine of the base required.
For example, let the sides be .34° and 47°, their loga-
K 3 rithms