Heating the air by steam is the next most healthy means; as the surfaces used are heated a little hotter, less of it answers the same purpose. The first cost is therefore less. It is the most rapid and convenient means of conveying heat to any distant point of anything now in use. Under the pressure of an ordinary boiler it will travel seven miles in one minute. The time I hope is not far distant when the subject of heating and ventilation will receive an amount of attention due to its importance. I believe then we shall have steam pipes laid through our streets, the same as gas and water now are. The present system of each man keeping up separate fires all over his house is as crude, and extravagant, and unnecessary as it would be for every man to make his own gas or have his own well for water. Where a steam furnace is used, two-thirds of the heating surface should be put below the floor and fresh air brought into it, and from there conducted to the rooms through large pipes. This warmed air should be let into the room at the floor, and an opening into an exhaust flue, two-thirds the size of the inlet, should be provided at the floor for the escape of the foul air. The remaining one-third of the heating surface should be exposed in the halls and some in the other parts of the house, to heat by direct radiation, but under no circumstances should a room or office be occupied _heated exclusively by direct radiation_ from exposed steam pipes. It is one of the worst, most unhealthy, _killing systems_ in existence. Steam furnaces require the evaporation of an additional amount of moisture as well as any other system of heating. According to Dr. Wetheral's investigation, it would require the evaporation on some days of nearly forty pounds of water every minute in the Senate Chamber to maintain the proper hygrometric condition. Probably one of the very best arrangements is to have a good steam furnace, with a large fresh air box letting in an abundance of air moderately warmed, and overflowing the house with this, and some direct radiation in the halls, and a good, bright, cheerful open fire in the family sitting-room. But if you cannot have a steam or hot water furnace, you can make a room very comfortable indeed with a stove, if you will but introduce all the fresh air required for the room directly against or on top of the stove. No stove ought to be put up without having a supply of fresh air from the outside, and a large evaporating vessel, kept constantly filled with water, with an opening in the heated flue near the floor for the escape of the foul air.