Of the engine there is nothing very special to be observed, as it is of the old construction, and, though perfectly efficient, not now to be imitated or adopted. It is a horizontal high pressure engine of about forty horse power, under the head of steam usually employed, though capable of exerting considerably more force, if called upon. There has been recently attached to it a singularly ingenious little machine, in the shape of a hydraulic regulator, of which great expectations are entertained, and which, in the very short time it has been tested, works to admiration, one week only having elapsed since its application. To attempt to describe this, or in fact any other complicated machine, in an illustrative article such as this pretends only to be, were an absurdity; for the operations of the simplest engines can be rendered thoroughly comprehensible, only—if at all—by thorough diagrams with numerical references, and then comprehensible only to scientific readers, conversant at least with the principles and working of the motive power, and the forces to be exerted by it. Ascending from the subterranean regions, which are, by the way, so constructed under an open and little occupied court-yard that even in case of any untoward accident the least possible damage would ensue, and certainly no upheaval of whole edifices, as by the explosion of a powder magazine, would be the consequence, we arrive next in the order of production at the great foundery, occupying nearly one half of the ground floor on the Broome street front. [Illustration: OLD STEAM-ENGINE, BROOME STREET.] Of this, although it furnishes the rude material, the first degree we mean from the actual raw metal for the whole establishment, the saw manufactory alone excepted, there is little to be noted worthy of particular attention by those who are familiar with the operation of furnaces, founderies and casting on a large scale, as in fact there is nothing in it unusual or novel, unless it be what struck us as both novel and unusual, the general absence of noise, confusion, din and turmoil, not to mention ill sounds, ill savors, and oppressive heat, which seems to pervade the whole establishment. This, ministering as it does largely to the comfort and well-being of all concerned, detracts somewhat, it must be admitted from the picturesque effect of the scenery, and its adjuncts. Even the neatness and cleanliness of the orderly and well conducted moving about each his own business noiselessly, and obeying a sign or the wafture of a hand, diminished the effect which we almost expect to feel in an iron foundery, a furnace, or a machine shop.