Alan,
I have to say that your blast furnace is exquisite. I hope people appreciate the difficulty of such a build and the detail you have put into it. I have seen a lot of disappointing O scale blast furnaces over the years. Many folks mistakenly think they can slap an HO Walthers kit (which is small even for HO) on the layout and call it a day. Blast furnaces are HUGE - even the small ones like Carrie Furnace.
It's such a complex structure and getting the proportions right is not easy. A lot of people have trouble with the base of the structure, but this looks awesome.
The other stumbling block (in my opinion) is the top (downcomer and skip hoist). Again, it's a matter of proportions.
I think you nailed this! 
George
