Welcome!

Hello and welcome to my blog site about slide rules. This represents the newest incarnation of my slide rule sites, the earliest of which was online in 1998, and now this site has been updated as of July 2022.  Since 1998, and through several different service providers, I have long had original slide rule related research, collecting information, and usage tips provided free for your enjoyment. There is a lot to see here, and through the links much of the slide rule research world is available. 

I have participated in a great deal of research on slide rules, starting with my work on the Doric series of K&E slide rules, and on the plastic rules in general, for the late Michael O'Leary's K&E XREF in the late 1990's and early 2000's. Clark McCoy also put in a huge amount of work on the XREF and deserves mention! The Doric tab will take you to one of my "Holy Grail" slide rules that I searched for for YEARS that came out of this research. 

I became fascinated with the Versalog, at the urging of Ted Hume, and continue to look for new things regarding Hemmi and the Versalog. I have searched for many years to find another "Holy Grail," the rumored, rarely seen all plastic Geotec Versalog II, and finally found one. The Geotec tab will take you there. The Versalog variants tab will take you to some interesting transitional variants of the Versalog. 

I put out the first ever comprehensive study of Relay/Ricoh Bamboo slide rules, which is preserved and still available on the Wayback machine, linked at right. This also contains the only look at the rare Nikkei branded bamboo slide rules, as well as an early bit of work researching Dietzgen slide rules. 

Finally, the newest research that I have shared is that surrounding what has previously been a mislabeled slide rule manufacturer. Click on the Pereles Bros. tab to see the result of an additional research project that spun off from the K&E Doric research project, which is still ongoing. 

I hope you enjoy! 

David A. Davis 

July 2022