At precisely half-past eight o'clock, on a grey February morning, two amiable-looking, middle-aged gentlemen left a medium-sized house of comfortable appearance, in the neighborhood of Hampstead, and commenced a walk undertaken them daily, in the interests of health, with the exception of Sundays, public holidays and a fortnight in August. There was sufficient resemblance between the two to proclaim them brothers-at first sight, indeed, they might have been taken for twins.