you've bought this for the right reasons by the sound of it, which is how it should be, but my opinion is that this is from the first half/mid C19 in date, but always ready to be corrected. Earlier bottles would more likely have had either a target/bull's eye, or flattened mushroom design of stopper.
Known as a 'canted square' - canted apparently derives from the flattened corners - mould blown then removed and attached to the pontil rod in order to finish the top rim. The fact that this is a 'square', and has a sharp pontil scar, are likely reasons for believing this to be older, but as we know sharp scars can occur on a lot of C19 material - and, again only my opinion, but the wheel engraving is suggestive of pteridomania - that Victorian passion for depicting images of leafy and ferny flora, and this style had a big fan club which started around c. 1840 ish. My opinion is that in this instance the clover leaves, if that's what they represent, are not indicative of an Irish origin - I've just ploughed through Phelps Warren and engravings showing shamrock do occur, but couldn't see any clover leaves - although have to admit I've really no idea what the difference between the two is.
Unfortunately, your backgrounds are busy and distracting - clear glass needs a uniform and preferably dark background to help illustrate detail - it's not easy to produce good photos of clear glass, but if you search the Board's archives we've had some very innovative and clever folk who have shared their methodology with hints on how to improve pix for clear glass. You'll also find the Board's archive a great glossary for meanings and definitions for some of the terms used here............ it saves having to explain terminology each time.
There appears to be a kick in the bottom of this bottle, and the scar might just be one of circular sort, not a full scar, and the kick might be there to avoid the need to remove the scar - i.e. an economy measure possibly. These hollow scars, if that's what it is, can be an indication of Continental origin - the pontil rod was hollow, unlike most British examples which were solid.
No idea as to origin - might be from anywhere as these things produced in vast quantities in most countries. Judging by past experience other replies will probably be deafening in their absence - it would be great if others would join in - we live in hope.
