Thanks for the help!

Still, it seems that Bit::Vector seems designed not to allow inheritance. Almost all the methods, such as shift_left(), check to see that they are handed a genuine Bit::Vector. If it isn't a Bit::Vector an error is generated.

I'm beginning to think that I need to use a different strategy. Perhaps I should make an object that has a USES_A rather than an IS_A relationship with Bit:Vector.

It should work perfectly the first time! - toma