Slide Rules

My father had [1] an Otis King, which is a helcial slide rule. I found another one in a charityshop for a very low prince, of course I bought it. I often show it to visitors, very few people outside my immediate circle of friends can work out what it is used for. I always thought those were a good idea since the 2 ends of the scale (effectively 1 and 10) coincide. You didn't have to think about which way to move the slide to ensure the answer was on-scale. Were there ever slide rules made for bases other than 10 (say scales from 1 to 8 or 1 to 16)? Those little 'move the sliders with a stylus and hook roudn for carry' adding machiens did esist for other bases. The octal and hexadecimal oens showed up on Ebay a few years ago. Unfortuantely they sold for about \pounds 500 each (due to their rarity) which was a lot mroe that I would spaend on a curiousity -tony