When first built in 1780, Leith Battery (Fort) had most of its guns mounted on these "traversing frames". This shows a 32pdr, Leith had 24pdrs (pdr being the weight of the shot in pounds, muzzle loaders were not measured by the diameter of the bore)
https://twitter.com/ssmirash/status/1304328534652080128
We can see from the plans (thanks NLS!) half of the battery here, with 24 pounders at 1-4, those at 2-4 being on traversing frames. In the centre, at 9, was a colossal 13 inch mortar, a terrifying weapon but largely ineffective against ships due to the difficulty of aiming it. 
This video shows a 24 pounder being loaded and fired by re-enactors at "Old Fort Henry" in Ontario, Canada. Notice it takes the best part of 3.5 minutes to complete the loading and firing drill.
The mortar was probably included as it could fire explosive shot, but more importantly could fire an illuminating shot for night actions. Here is a picture (source = victorianforts.co.uk/arming/13in.htm) of one in action.
The battery had a pair of smaller 18 pounders "en barbette" (rotating behind a shield) to protect the entranceways. These smaller weapons were handier and faster to reload.
And right down on the Newhaven (now Lindsay) Road level, a single 68 pounder "Carronade" for point blank use against ships trying to force their way into the Port of Leith
The rest of the defences all pointed landward, with loopholes along the walls and corner bastions to provide "enfilading" fire (i.e. shoot lengthways along the face of a wall). Although the fort was not designed or intended to resist a siege, this was purely self defence.
• • •
Missing some Tweet in this thread? You can try to
force a refresh
