# the brooklyn bridge, and why it is the second folder

a bridge the product opens. `../index.html?src=brooklyn-bridge` is the app on it. an elevation, not a
plan; 1883, not 2014; and the opposite case from `../floor-73`. there the owner withheld everything
and the whole drawing is blue. here the bridge was measured and the measurement is public, so the
drawing is ink, and the blue is exactly what the measured sheet leaves out. one renderer, one log,
one grammar: the product is not a floor plan viewer, and showing only the floor said it was.

`build.py` writes two files. run `python3 build.py`.

- `model.json`, 1 kB: the reference. a datum, mean high water, and six facts. the sheet is a scan,
  and a scan has no members, so nothing else arrives.
- `log.json`, 194 kB: the session. twelve messages, 529 members in the messages that drew them.

feet, x from park row, y above mean high water. the numbers are not here: they are
`../../design/brooklyn-bridge/geometry.py`, the same file the deck's elevation and the hand's sketch
read, so the product cannot disagree with the brand about the bridge.

## what is ink

everything HAER NY-18, sheet 1 dimensions (`../../design/brooklyn-bridge/SOURCES.md`): the spans,
930 · 1595'-6" · 930; the towers, 59' through and 276'-6" above mean high water; the anchorages, top
at 129'; the roadway, 119' at the towers; the main cable, straight to the anchorages and a parabola
with 128' of sag between the towers.

## what is blue, and why

| what | drawn as | why it is assumed |
|---|---|---|
| suspenders | 15' on centre, then 7'-6" | the measured sheet draws them and dimensions no spacing. 15' is the brand elevation's, chosen to read |
| stays | fourteen a side, then twenty-five | counted off the elevation, not on the sheet |
| reach of the stays | 448' each way from a tower | read off the elevation. no source here says how far they run, so it stays the machine's even after the redline |
| underside of the truss | 17' under the roadway | `geometry.py`'s depth, not on the sheet. with the roadway at 144' it puts mid span at 127' clear against a dimensioned 135'. the session holds this and the engineer takes it away to settle; it is not settled here |

## the redline

message 9: *suspenders at 7'-6" on centre, not 15'. and twenty-five stays a side, not fourteen.*
both numbers are frank griggs jr., "brooklyn bridge, part 2", structure magazine, november 2016,
https://www.structuremag.org/article/brooklyn-bridge-part-2/ : "spaced 7½ feet on center", "25 stays
on each side of the tower per cable". an elevation shows one cable plane, so twenty-five a side is
one hundred drawn. message 10 picks both up: 208 suspenders added between the 204 it had, the stays
respaced over the same reach. it stays blue. red changes what the machine drew; only message 12 signs it.

## the people

l. moreno, pe, and the licence number are a demonstration, like d. ruiz on floor 73.

## rights

the geometry is from a us government measured drawing, public domain. the drawing is ours. it is an
elevation for reading, not for construction, and the title block says so.