Cast Iron "S" On Outside Of Buildings

[chamois]

I've seen what appears to be on an old house on the side of an English canal that has what appears to be a pair of large, metal (possibly cast iron) structures shaped in a "S" shape on on the front of the building either side of the central front door just below the upstairs windows. They are always in pairs and one resembled a normal "S" while the other is a reversed "S". They are about 60cm high.

I've seen a photo this morning of a windmill with them:

https://www.alamy.com/stock-photo-lytham-windmill-built-in-1805-on-lytham-green-lytham-lancashire-england-138318895.html

They can be seen just below the top floor window on the windmill.

Are they some form of an old method of brickwork or stone reinforcement for these buildings? They are obviously only found on old buildings and I'm puzzled why they are always in pairs with one "S" always reversed.

Thanks for any suggestions.

[chamois]

If it helps, these things always seem to be painted black no matter what the colour of the building.

[bhg481]

As you suspect they're for reinforcement. A rod connects the two on opposite sides of the building to stop the wall bowing out.

[Peter Pedant]

bar between them and it helps to keep the building standing.
For a house buyer it is a sign of subsidence - so dont buy!

for the canal hosue, it just badly built, as mining is not allowed within... 50 m of a canal ( I think ) - there fore no mining subsidence

[davebro]

If you have a bulging wall you put the Ss on opposite sides of the building joined by a steel bar running through the building. You heat up the bar so it expands then tighten the nuts on the outside. When the bar contracts it pulls the walls into shape.

[SlackAlice]

Think you will find they are "Anchor Plates" to reinforce the walls against lateral movement.

https://en.wikipedia.org/wiki/Anchor_plate

[chamois]

Thank you all for clarifying. I'm very grateful and will puzzle no more about these.