After publishing the image of the "enhanced" Ripper's pentagram, which shows how some of the victim-locations lie on the lines (thus supporting my claim that the pattern is not coincidental), and depicts the bearing of the pentagram's center relative to St. Paul's Cathedral, it occurred to me that the fact that two of the vertices coincide with the east-west axis can be construed as a hint that the pattern's intent was to convey the idea of something rising above the horizon, i.e. dawning. It just so happens that the Golden Dawn was established the same year - 1888.
I've also been meaning to mention a perspective on the year 1888: that if the first two digits and the last two digits are considered as separate numbers, it can be converted into 9 and 8x11. Perhaps that's how those behind "Jack the Ripper" saw it.