Tabby walls were somewhat easy to make (particularly when you had slaves to do it for you), so one imagines that more than one batch of such walls were whipped up over Fort Dorchester's lifetime...I would like to think that the fort's original bastions fit together better than this? But then it's not as though anyone was trying to make a watertight seal. This gap isn't big enough for a person to wriggle through, but a sword or a pike could have absolutely been snaked through there!