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Log Tables

lostmyway

While I have a good idea how log tables work, I'm still in the dark as to how they are compiled.

I gather some bloke name 'Napier' originally invented them but what method did he use?

Any mathematicians' contributions would be appreciated. 

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  • Former Member
    Former Member

    I got into trouble because I took my parent's typewriter to pieces to see how it worked.

    Slide rules are just a handy way of using logs and anti-logs to perform multiplication and division. They just hide the lookups that you need to do behind a non-linear scale. I bought my first slide-rule because it looked neat but I had no idea what it was for - I just wanted one of those.

    Logs are all calculated by long multiplication and long division with the aid of comptometers (back in the day) and the like. As an example where you want to calculate things with decimals such as 0.17 you can by calculating the log of the number - in this case 17 and then calculating the log of one hudredth of that - 0.17 by subtracting the log of 100 from the log of 17. You only have to calculate the logs of the whole numbers and the rest is done by subtracting the logs of factors of 10.

    Not sure if that makes sense but it made me think of times past!

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  • Former Member
    Former Member

    I got into trouble because I took my parent's typewriter to pieces to see how it worked.

    Slide rules are just a handy way of using logs and anti-logs to perform multiplication and division. They just hide the lookups that you need to do behind a non-linear scale. I bought my first slide-rule because it looked neat but I had no idea what it was for - I just wanted one of those.

    Logs are all calculated by long multiplication and long division with the aid of comptometers (back in the day) and the like. As an example where you want to calculate things with decimals such as 0.17 you can by calculating the log of the number - in this case 17 and then calculating the log of one hudredth of that - 0.17 by subtracting the log of 100 from the log of 17. You only have to calculate the logs of the whole numbers and the rest is done by subtracting the logs of factors of 10.

    Not sure if that makes sense but it made me think of times past!

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