"Ma'am. A pleasure to meet you as well." He offered her a polite nod. "Ah, and please, do sit down, both of you." In theory he was the host, after all -- best to be polite.
He waited for them to settle before he sat down himself. "I've been wanting to build a difference engine for a while but I couldn't ask anyone to build some of those parts for me. So I'm hoping to cobble it together from this and that."