I have to say that it looks like an early 20th century central European fireman's axe to me, but these can be problematic to place as they are somewhat 'related' (Boarding/Fireman's/Sappers......)
http://www.vikingsword.com/vb/showthread.php?t=16469
Have a look at this completed eBay listing for an axe described as an Antique German fireman's axe:
http://www.ebay.co.uk/itm/ANTIQUE-GE...-/360523052060
If yours is a French Boarding axe then what sort of date, early 19thC?
It looks very clean and machined to me, that also makes me think 20thC.
Like I say though, these are problematic at best. And your axe is certainly very similar to some definately genuine French boarding axes of the first half 19thC that I've seen.
Don't suppose that there are any stamps or markings?