How high was Nelson?

Since that fateful night of 8 March 1966, I have often wondered exactly how much of Nelson's Pillar was blown up. I went for years thinking that it was only the very top of the column. I was possibly influenced in this by the little bit of the plinth that remained perched on the top of the blown up column.

In more recent times I realised that a significant portion of the column itself had been blown away and figured that the explosion had been about two thirds the way up the column. Then I left it at that.

Today, via a link in a comment on the blog Come Here To Me!, I came across a video of the explosion, and have extracted the above still shot. Well it wasn't the actual explosion as I don't think there were still buses running up O'Connell Street at half past one in the morning in those days. Nightlink was still to come. However I was intrigued at where the video had put the point of explosion, about half way up the column. This may have more to do with the song than with any forensic analysis, so I thought it time to have a go at some of the latter.

The photo below shows an earlier shot of the pillar from Henry Street overlaid with one of my own photos from March 1966. It shows quite clearly that the point of explosion was almost two thirds (63%) up the column as I had already guessed from a previous crude measurement exercise.