The latest Ada Wilson attack-site has a bearing of 74.72 degrees (15.27 above the east-west axis) relative to the east end of St. Paul's Cathedral, and not the precise 75/15 degrees I was hoping to find. It is more precise (74.95/15.05) relative to the dome, but if the dome is used as a reference, then the bearing to the Durward location is thrown off by about 0.2 degrees.
But I still think that the site of the attack was supposed to take place at precisely 75 degrees, or that it was intended to be close enough to express this intention, and to align with the Durward site to “point to” St. Paul‘s Cathedral, in combination with the line defined by the Herniques and Mitre sites. I consider this error to be negligible, partly because it’s impossible for me to know the exact coordinates of most of the significant points without someone with a PhD in Ripperology going to the exact spots and taking readings with a precision GPS instrument.
The timing of the attack was interesting: one day after a full Moon, shortly after the spring equinox, and on a date which yields an interesting numerical combination: 3/28/1888, the digits of which add up to 38, which in turn yields 11, the number of black magic, which Satanism pretends to be.