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The construction of the wonderful canon of logarithms

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Construction <strong>of</strong> <strong>the</strong> Canon, 29<br />

sine and <strong>the</strong> table sine (by 40), ei<strong>the</strong>r both<br />

Hmits or one or o<strong>the</strong>r <strong>of</strong> <strong>the</strong>m, since <strong>the</strong>y are<br />

almost equal, as is evident from <strong>the</strong> above example.<br />

Now <strong>the</strong>se, or ei<strong>the</strong>r <strong>of</strong> <strong>the</strong>m, being found,<br />

add to <strong>the</strong>m <strong>the</strong> limits above noted down, or else<br />

subtract (by 8, 10, and 35), according as <strong>the</strong> given<br />

sine is less or greater than <strong>the</strong> table sine. <strong>The</strong><br />

numbers <strong>the</strong>nce produced will be near limits between<br />

which is included <strong>the</strong> logarithm <strong>of</strong> <strong>the</strong><br />

given sine.<br />

Example,<br />

Let <strong>the</strong> given sine be 9999975.5000000, to<br />

which <strong>the</strong> nearest sine in <strong>the</strong> table is 9999975.<br />

0000300, less than <strong>the</strong> given sine. By 33 <strong>the</strong><br />

limits <strong>of</strong> <strong>the</strong> logarithm <strong>of</strong> <strong>the</strong> latter are 25.0000025<br />

and 25.0000000. Again (by 40), <strong>the</strong> difference <strong>of</strong><br />

<strong>the</strong> <strong>logarithms</strong> <strong>of</strong> <strong>the</strong> given sine and <strong>the</strong> table sine<br />

is .4999712. By 35, subtract this from <strong>the</strong> above<br />

limits, which are <strong>the</strong> limits <strong>of</strong> <strong>the</strong> less sine, and<br />

<strong>the</strong>re will come out 24.5000313 and 24.5000288,<br />

<strong>the</strong> required limits <strong>of</strong> <strong>the</strong> logarithm <strong>of</strong> <strong>the</strong> given<br />

sine 9999975.5000000, Accordingly <strong>the</strong> actual<br />

logarithm <strong>of</strong> <strong>the</strong> sine may be placed without<br />

sensible error in ei<strong>the</strong>r <strong>of</strong> <strong>the</strong> limits, or best <strong>of</strong> all<br />

(by 31) in 24.5000300,<br />

Ano<strong>the</strong>r Example.<br />

LET <strong>the</strong> given sine be 9999900.0000000, <strong>the</strong><br />

table sine nearest it 9999900.0004950. By<br />

33 <strong>the</strong> limits <strong>of</strong> <strong>the</strong> logarithm <strong>of</strong> <strong>the</strong> latter are<br />

1 00.0000 1 00 and 100.0000000. <strong>The</strong>n (by 40) <strong>the</strong><br />

difference <strong>of</strong> <strong>the</strong> <strong>logarithms</strong> <strong>of</strong> <strong>the</strong> sines will be<br />

.0004950. Add this (by 35) to <strong>the</strong> above limits<br />

and <strong>the</strong>y become 100.0005050 for <strong>the</strong> greater<br />

D 3 limit,

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