Thank you Arthurwg.
Drew Weley is right, till a certain extend, and I got away...
But, the atmosphere was such that this approche was, in my eyes, the best one.
I first measured the light and saw that it was quit impossible to shoot without a tripod, bud I didn't carry one (didn't I say I don't like them).
So I set the shutter at 1/15th and the aperture full open and hoped for the best. Luckily the SWC has no mirror!
I always carry at least two film chassis, one with Tri-X at box speed and one at 1000 ASA. But I cheat a little: the Tri-X at 1000 ASA is actually processed at 1600 ASA as to keep the shadows somewhat open. After the demise of AGFA, Tri-X/D-76 has replaced my so beloved AgfaPan 400/Rodinal which gave more tonality and exposure play.
I developed according the time table for D-76 1+1 but used the E-76 1+1 formula by Chris Patton (thank you Chris). I don't like Metol and Hydrochinon as it gives me red and itchy traces om my skin.
BTW, I think that if I had played by the rules and used a tripod, and exposed for the shadows as usual, the lower parts and the columns could be exposed nearly correct but the highlights in the arches would have been overexposed and, perhaps, blowend. The Tri-X at box speed and processed in E-76 (= D-76) could not have fully managed this situation, and the Zone System on roll film isn't that obvious...
And everything, would be sharper and perhaps better, wouldn't it?