“The whole length of cast iron hot water pipe is about 600 feet, and with the portion of the heater within the main air cell or reservoir, and the smaller wrought iron tubes connecting the extremes of each of the six pipes with the upper and lower ends of the boiler, constitutes a radiating surface of over 700 square feet. The effective fire surface of the boiler is probably about 30 superficial feet, and about 60,000 cubic feet of space above in the three corridors, and the rooms opening upon them, are to be heated. “The amount of anthracite consumed in the twenty-four hours of our coldest weather, is not far from 400 lbs.; the water in the extremities of the pipes receiving it from the heater, rarely exceeds 180° F. and falls off about 20° at its point of re-entering. “All these expressions, however, are quite indefinite without taking into consideration the extent of change required in the air. It is obvious that by closing the damper which commands the ventilating shaft, the relations of temperature of the air, and of the pipes would at once sympathize. With the active power of the shaft, it is certain that any possible amount of ventilation may be attained. Indeed, it is probable that the present shaft is equal to the demands of the remainder of the male wing in addition. The escape of the steam pump is injected into the centre of the ventilating space, giving us, for some hours daily, the aid of this recently adopted and exceedingly efficient means of ventilation. “While a sufficient time has not yet elapsed to stamp our apparatus with the seal of experience, the only test of such appliances in the mechanical arts, yet we are authorized to declare that, as far it has been tried, it promises all that could be desired in supplying a full, certain, and manageable amount of air, in its highest hygienic conditions. “The cost of getting up a complete system of hot-water warming and exhaustive ventilation in a country where few examples or approximate specimens are to be found--in a climate which nullifies all European experience--where all parties, suggesters and mechanics, are obliged to acquire a certain experience as they go along, must be much greater than when this subject shall be well understood and generally adopted, as it eventually cannot fail to be. Independent of making the flues and ventilating chimney, items which in new undertakings would naturally come under the head of construction account, the expense of our undertaking will fall considerably below a thousand dollars, and we are satisfied that with the experience acquired in this single trial, it could be gone over again at a very considerable reduction of cost.”