1851 Calculating Machine
1900 Simplex Slide Rule
Worldwide Slide Rule Patents
Starting in the 1800's, inventors began filing for patent protection for their slide rule designs. The patents listed
in this gallery are specifically for those apparatus that deal with mathematical operations, for the
most part with logarithmic scales. Most take the shape of common slide rules, either linear or circular,
but in some case more complex inventions, which used logarithms, are included here as well as they progressed toward
the automation of math calculations. I also include the TI and HP electronic slide rule calculator patents.
This gallery is beginning with over 1000 patents, and still more as they are found. Please help in this endeavor if you help search the public databases in your country. Thank you.
Work in Progress
In the meantime another excellent resource is Rechner Lexicon Patent Page,
a German wiki site which includes all mechanical computing devices, and of course Europe's
Worldwide Network of Patent Databases, espacenet.
1937 Duplex Slide Rule
1975 Electronic Slide Rule