These are very peculiar brackets and may possibly be early armless brackets! I do not know for sure though!

Google Maps Link: https://www.google.ca/maps/@42.7680898,-80.9846978,3a,90y,64.77h,106.43t/data=!3m6! 1e1! 3m4! 1sb7Y4jMVr4Pxa4rxW2pjPog! 2e0! 7i13312! 8i6656

Photo Credit: Google Maps