Whilst I'm no expert on Briscoes that originate in Brockville, Ontario,
Canada, the information I have would tend to suggest that the Briscoe
you have is not a 1914/15 Briscoe, but rather a later model, possibly
1916. The earlier 1914/15 Briscoes were unique in that they had a
single headlight in the middle of the radiator shroud - rather than the
conventional two headlights which are shown in your picture.
I'll try to upload a period photo I have of a 1914/15 Briscoe with a
similar cloverleaf body style to your discovery.