The division of buildings into horizontal compartments, rather than vertical ones, is so much more desirable, where land is expensive, that inventors have almost exhausted their ingenuity in devising thoroughly fire-proof floors. It is obvious, however, that the division of a building by vertical fire-proof partitions, is a matter so easy of accomplishment, that it is questionable whether the horizontal division, so beset with practical difficulties, so expensive, and withal so much less to be depended upon, even when the best systems of construction are used, is ever economical, even where ground is expensive. I even question whether it is of any use to build iron floors, or floors with iron supports, for buildings to contain goods; brick piers and groined arches are alone reliable. If you divide horizontally you must have stairways within and windows on the exterior, both of which welcome the ascending flames. You may enclose your staircase in a fire-proof enclosure, and you may put the heaviest iron shutters on your windows, but you must have doors through which to gain access from your stairways, and you must open your shutters when you want light. There is a contingency that these traps may be set when the enemy comes, and then all your expensive floors represent so much wasted capital. As yet, I believe, that no buildings in this vicinity, built purely for storage purposes, have been constructed entirely of fire-proof materials, except the St. John’s Depot of the Hudson River Railroad Company. I am not aware that any attempt has been made in these buildings to stop a conflagration among the goods on storage either by horizontal or vertical compartments. The floors, to be sure, are of iron and brick, non-combustible, but with hoistways; and it is not difficult to conjecture, even supposing that all horizontal openings and iron shutters were closed, what would be the result of a fire raging on one of those floors, hundreds of feet in expanse.