eleven o'clock
`` Certainly . I was here from one o'clock -- say between one and two . '' `` And I was here also . From eleven o'clock till two I was in this very room working out some calculations at this very table by the aid of my reading-lamp , no other light being in the room , or even in the house , as far as I know . It is one of my fads -- as fools call them -- to work in a large , dark room with one brilliant light only . Therefore you could not possibly have been in the house , to say nothing of this room , on the night in question . '' David nodded feebly .