There's a nice blog post here about the differences between then and now, which as always make for a fun read. While it's quite nice to learn about the words that haven't made it this far (marconigram, kinematograph and so on), my favourite thing is the style of the older edition. It seems so quaint nowadays.
A terrier, for instance, is a
kind of active & hardy dog with digging propensityAnd to greet is to
accost with salutationAnd relatedly, the blog post notes that while the OED defined cancan simply as 'indecent dance', Percy Scholes, editor of the first Oxford Companion to Music (1938), wrote that
Its exact nature is unknown to anyone connected with this Companion.Quite right too.