You know I can't? - I looked earlier and couldn't find a thing, except for a small map of Halifax's earliest waterworks plans - and 200 years may be fifty year exaggeration. All I can find are the skateboard park, which has completely obliterated it.
It was egg-shaped in outline, about five feet deep, walled to ground level in typical Halifax mortared ironstone, or angelstone it's called sometimes. When I moved to Halifax in 1969, it was dry in summer and had a dirt bottom, filled and frozen for skating in winter. The willows around it were huge old things. It was quite large, but i can't recall well enough to estimate - big enough for a fair number (forty-fifty people?) to ice-skate rounds on.