When a section of the wraparound windows at Alexia’s Pizza in Belfast suffered a long diagonal crack recently, neither the owner of the business nor the glass repairmen who came several days later seemed to know why it had happened, though both ruled out an accident or act of vandalism.

Alexia’s owner Ted Rakis said he first noticed a small diagonal crack in the lower corner of one of the windows on the High Street side of the business. While covering the crack with duct tape, he noticed that by some trick of physics it had jumped the mullion to the next pane. Rakis touched the leading edge the of the crack and before his eyes it spread diagonally from the bottom right to top left corner of the pane, a distance of close to 10 feet.

That was pretty much it for the window.

And the duct tape, too, which Rakis used not only to cover the now-huge crack, but to make a tight grid over the entire pane, creating a low-tech version of safety glass until the window could be replaced.

Workers from Dirigo Glass, who were on site taking measurements for a new pane Thursday, Aug. 11, guessed that the building must have settled or shifted, causing the initial crack. On the Main Street side of the pizza parlor, two other panes bore smaller cracks that Rakis said predated the one on High Street.

On a purely geometric level, the older cracks — a pair of right triangles at the bottom corners of two adjacent panes — looked as though they had gone as far as they could go, but then so had the other one.

Rakis said another window on the High Street side had cracked in a similar fashion around three years ago, and had since been replaced. More recently a different window was broken as the result of someone being pushed into it after a squabble migrated from a nearby bar to the sidewalk outside the pizza shop.

In short, this wasn’t the first time that Rakis was overseeing a glass repair. And as he chatted with the workers from Dirigo Glass, he seemed resigned to the appearance of the occasional mystery crack.

Maybe he would decorate all the windows with duct tape, he joked.