Canadian 18-PR slide rule help needed.

[Quatermass]

Looking for some help from our Canadian members.
I have an 18-PR slide rule marked 'RULE FOR Q.F. 18-PR. GUNS USED FOR COASTAL WORK. EXAMINATION BATTERY ST. JEAN. I.O. QUE'.
The rule is handmade from wood and must be unique.
Does anyone have any information on the 'St. Jean' Battery or a date?
Thanks in advanced.

 

[Investment]

Hi Quatermass,
The I.O. on the slide rule refers to le d'Orlans (Orleans Island).
Cheers,
Invest

Saint Jean Battery
(1939 - 1945), Saint-Jean
Two 18-pounder guns were located here on le d'Orlans.
Nearby at Maheux Bay were examination batteries for WWI (1914 - 15), consisting of one 60-pounder gun and one 12-pounder gun.

http://www.northamericanforts.com/Canada/qc2.html#new

Saint-Jean-de-l'le-d'Orlans is a municipality in the Capitale-Nationale region of Quebec, Canada, part of the L'le-d'Orlans Regional County Municipality. It is situated on the south-east side of Orlans Island

http://en.wikipedia.org/wiki/Saint-Jean-de-l'Île-d'Orléans,_Quebec

 

[Quatermass]

Thanks Investment, that's great.
I wonder if there's a museum over there that would like it?
Thanks again.