This is another H.M. Caldwell Co. 1900 edition…also seemingly from their ‘Remarque’ series in some way. I have another Rubaiyat like this from the same year.
That other edition is very much like this one on the inside. The big interior difference that I can note is that this edition has this combo FitzGerald Icon/Festina Lente symbol on the front cover page. I recognized it as recently a visitor reached out with another 1900 Caldwell copy that also had this symbol that wanted more info. I couldn’t figure out much there besides what I found on Wikipedia: it being related to that Latin phrase imprint/printer’s mark of sorts.
This edition stands out with its red cover and dark case. The case I have is beaten up and has been reinforced with tape. It has a label on one of its edges. I am not sure if it’s original to the series or was made for protection. I’d lean towards original, given the condition.
Update 10/2023: Updated copy as I have a new understanding of what the remarque is.