Next came the inner arch - the one that will join to the clay dome. I split the free bricks I'd been given in half (these are solid bricks, with about two inches of one corner cut off) and used a mix of 50% fireclay, 50% grog as a 'mortar'. This wasn't that easy to work with, and was more like moulding a clay arch with bricks in it rather than building a brick arch with mortar. I used some of the chopped corner bricks for the top of the arch to encourage the smoke upwards and up the chimney. Here's the result:
The gap between this inner arch and chimney will be filled up with my insulating mix later on to seal all these gaps. It's below freezing tonight, so I've put a 100W light bulb on a cable below the wet clay and brick arch to stop it from freezing solid. Hope this works.