Have I interpreted the Diamond Marks correctly?

Hello everyone - I've acquired a number of items, one of which is a cast iron fireplace.

From my rudimentary skills I think this was made in 1866, on the 3rd July. Anyone able to confirm or correct me please? I've no idea what the other markings are or mean - I assume perhaps something about the maker?

I'm hoping to sell this and a number of other items so knowing a bit more about all the pieces I have will be useful.

Thanks and have a lovely day.

 

Must weigh a ton.

 

What leads to this conclusion? Such a specific date is more likely to be for a patent.

 

Especially since it is a registration mark.

 

Sorry I mean to say that this was when the patent design was registered.

But I'm interested to find out what the numbers and letters in italic next to the mark are - perhaps the specific model number and designer initials?

 

What size is it?

 

I see the letters to the right of the lozenge as No (superscript), numero.

 

That says No 52 + 38 in .

I bet it's 52 inches tall and 38 wide.