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I actually stumbled upon the British Library's copy, and promptly photographed every page. My only theory on the strange range of styles is that it might be meant for older women who grew up in, and were used to, a particular style of corset. There are 34 years between when it was published and 1890, and fair amount of women would have grown up with a shorter corset with a higher under bust, and want to keep it that way. I also think this was meant for dress makers who might begin catering to slightly older women who wanted to hang on to their older styles. Not everyone embraced modernity.