Anomalous

Sometimes you learn a lot when you see something that doesn’t make sense. For example, seeing terra-cotta block making up the partitions around a closet in a tenement:

Old-Law tenements (pre-1901) typically have all wood structure within their exterior masonry walls. Depending on how much they’ve been altered, they may have more or less fireproofing, particularly if we count deafening – the use of unreinforced concrete or other inert fill over wood joists – as fireproofing. New-Law tenements (1901-1929) and apartment houses constructed under the Multiple Dwelling Law (after 1929) have fire-rated structure at the first floor, and at public hallways. So you might see terra cotta partitions along the public hallways in a later building…but this is an Old Law tenement.

The short answer is that this was once a dumbwaiter shaft, and as a vertical shaft was fire-rated even in an unrated building. Various horrendous fires in New York in the mid- and late-1800s had brought home the danger that flammable shafts create in buildings, allowing uncontrolled fire spread. A wood-framed dumbwaiter shaft can spread fire from one floor to another in under a minute, and can get fire going on every floor in a building in a few minutes.

My thanks to Ellen for the photo and noticing the anomaly.