English: Page from Napier trigonometric table on display at the Computer History Museum. From CHM's display label: "Mirifici Logarithmorum Canonis Descriptio, 3rd edition, and Logorithmorum Canonis Constructio, 2nd edition, John Napier, Scotland, 1620 (1st edition 1614)

Michael Stifel (Germany), Jobst Burgi, (Switzerland), and John Napier (Scotland) independently invented logarithms. Napier's book, published only near the end of his life, first popularized their use. Loan of Gwen and Gordon Bell, B210,82"

The page gives values between 19 and 20 degrees in one minute increments. The left-most column shows the number of minutes to be added to 19 degrees. The far right column shows the co-angle (90° - x), from 70 to 71 degrees, reading up. Adjacent to each column is the sine of that angle, followed by the absolute value of the natural log of the sine. One can obtain cosines easily by reading across the page. A sign reversal give secants. The middle column gives the difference between the two logs, which is the natural log of the tangent function (cotangent if you reverse sign).