Small Carronade model - 68 pdr.

There seems to be some confusion between sodium nitrite and sodium nitrate

Roy

No confusion, the recipe calls for both

Oak, 218 years

Gunnades from Falkirk so probably by Carron.

Sorry, couldn't resist...

Doesn't the nitrate give you the nitrite plus oxygen?

IIRC this works for potassium, sodium and silver nitrates.

The Oak may not effect wrought iron to the same degree as carbon steel(even low carbon). Pure iron is very rust resistant.

Ian S C

Well, I shall just have to wait 202 more years to see whether the steel trunnions on my 24-pounder stay the distance...

Robin, I had to look up 'Gunnade' - but it turned out to mean what I thought it might from your photo. It looks as if the capsquares are pivoted from the forrard end, opposite to a long gun. I wonder what governed that?

The capsquare pivot is the top of a long bolt that goes all the way down, through the axle bar and nuts on from below. It has to be over the axle

OK, I’m going to show my ignorance now. What does OAL mean?

Brian

Thanks. That had crossed my mind but I’d dismissed the idea on the basis that overall was one word.

Brian

For me the most likely explanation is linked to the longstanding and current description for the length of a boat / ship / vessel etc

LOA Length Over All

Another term is LBP Length Between Perpendiculars which is more used in Naval Architecture as in basic terms it ignores length that is not in the water.

The steel/oak combination is unlikely to rust in a dry home environment but you could wax the metal before inserting in the holes. cf oak machinists toolboxes.
Wrought iron, especially when oxidised by the blacksmithing process to form old items is quite resistant to rusting. My garden gate hinges have no visible corrosion or rust after 80 years on an elm gate then 40 on an oak one. However the mild steel coachbolts used for their second round fixing are in a bad way inside the timber but fine outside in the exposed areas. The handmade nails I took out of the remains of my 120 yr old oak field gate are good to use again. (but will be used in something more classy)

In many parts of NZ, rural fences are constructed with high tensile galvanised steel wire with wooden posts, between these posts are 3 or 4 steel posts made of 8 mm x 30 mm hot rolled mild steel, in some parts of the country these do not last very long. In years gone by these standards were made of wrought iron, there are examples of these dating back to the beginning of the 20th century. In Central Otago (very dry by NZ standards) there are some early wire fences, made of unplated wrought iron wire, it is somewhat thicker than the old #8, maybe 3/16" dia, no pitting or rust, and if the animals have been rubbing against it, highly polished. Main disadvantages are, it doesn't hold tension because it stretches, it is very heavy because of the extra diametre, you can;t buy it 'cause they don't make it any more.

Ian S C

I can see that's the case for the gunnade carriages in the picture, but for long guns it seems to be the capsquare keeper-wedge eyes that are bolted through the axletree. In both cases it's at the front end of the capsquare.

I just wondered if there's any engineering logic in that, or preference by the maker, or just random variation.

Edited By Mick B1 on 17/09/2018 14:49:27

Not a clue. I am more in it for the big clouds of stinky smoke than the the technical guff