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The construction of the wonderful canon of logarithms

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Construction <strong>of</strong> <strong>the</strong> Canon. 23<br />

way, if you please, continue <strong>the</strong> <strong>logarithms</strong> <strong>the</strong>mselves<br />

in an exactly similar progression -with little<br />

and insensible error ; in which case <strong>the</strong> logarithm<br />

<strong>of</strong> radius will be o, <strong>the</strong> logarithm <strong>of</strong> <strong>the</strong> first sine<br />

after radius (by 31) will be 1.00000005, <strong>of</strong> <strong>the</strong><br />

second 2.00000010, <strong>of</strong> <strong>the</strong> third 3.00000015, and<br />

so <strong>of</strong> <strong>the</strong> rest.<br />

34. <strong>The</strong> difference <strong>of</strong> <strong>the</strong> <strong>logarithms</strong> <strong>of</strong> radius and a given<br />

sine is <strong>the</strong> logarithm <strong>of</strong> <strong>the</strong> given sine itself<br />

This is evident, for (by 27) <strong>the</strong> logarithm <strong>of</strong><br />

radius is nothing, and when nothing is subtracted<br />

from <strong>the</strong> logarithm <strong>of</strong> a given sine, <strong>the</strong> logarithm<br />

<strong>of</strong> <strong>the</strong> given sine necessarily remains entire.<br />

35- <strong>The</strong> difference <strong>of</strong> <strong>the</strong> <strong>logarithms</strong> <strong>of</strong> two sines must be<br />

added to <strong>the</strong> logarithm <strong>of</strong> <strong>the</strong> greater that you may have<br />

<strong>the</strong> logarithm, <strong>of</strong> <strong>the</strong> less, and subtracted from, <strong>the</strong> logarithm<br />

<strong>of</strong> <strong>the</strong> less that you may have <strong>the</strong> logarithm <strong>of</strong> <strong>the</strong><br />

greater.<br />

Necessarily this is so, since <strong>the</strong> <strong>logarithms</strong> increase<br />

as <strong>the</strong> sines decrease, and <strong>the</strong> less loga-,<br />

rithm is <strong>the</strong> logarithm <strong>of</strong> <strong>the</strong> greater sine, and <strong>the</strong><br />

greater logarithm <strong>of</strong> <strong>the</strong> less sine. And <strong>the</strong>refore<br />

it is right to add <strong>the</strong> difference to <strong>the</strong> less logarithni,<br />

that you may have <strong>the</strong> greater logarithm<br />

though, corresponding to <strong>the</strong> less sine, and on <strong>the</strong><br />

o<strong>the</strong>r hand to subtract <strong>the</strong> difference from , <strong>the</strong><br />

greater logarithm that you may have <strong>the</strong> less<br />

logarithm though corresponding to <strong>the</strong> greater<br />

sine.<br />

36. <strong>The</strong> <strong>logarithms</strong> <strong>of</strong>similarly proportioned sines are equidifferent.<br />

This necessarily follows from <strong>the</strong> definitions <strong>of</strong><br />

a logarithm and <strong>of</strong> <strong>the</strong> two motions. For since by<br />

C 4 <strong>the</strong>se

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