Does "though such was his habitual sobriety of demeanour that he was never known to laugh" mean "this was his habit to temper his hard manner with smiles but he was never known to laugh"?
he received with affability the innumerable visitors from every part of the world who came to converse with him in regard to the views of which he was the recognized exponent, answering questions and objections, explaining difficulties, and giving information to all serious inquirers, with whom he talked with freedom and animation, his face occasionally lighting up with a genial and pleasant smile, though such was his habitual sobriety of demeanour that he was never known to laugh.
"The History of Spiritualism," by Arthur Conan Doyle
he received with affability the innumerable visitors from every part of the world who came to converse with him in regard to the views of which he was the recognized exponent, answering questions and objections, explaining difficulties, and giving information to all serious inquirers, with whom he talked with freedom and animation, his face occasionally lighting up with a genial and pleasant smile, though such was his habitual sobriety of demeanour that he was never known to laugh.
"The History of Spiritualism," by Arthur Conan Doyle