Studied from its original page

Graphical string-lining chart

graphical method of string-lining curves (Church) · graphical determination of the curve offsets

Made by: H. M. Church, Division Engineer, Baltimore & Ohio Railroad, Baltimore
Year: 1915
Field: Engineering
Kind: Computing chart
Room: Change over time

Not shown here: its rights are not cleared

See the original page — unnumbered figure 'An Example of the Graphical Determination of the Curve Offsets', printed p. 130 (archive leaf n47)

Test A passes (published 1915) but test B cannot be decided: the author is a railway engineer with no Wikidata record and two web searches found no biography or obituary, and a man writing in 1915 could have died after 1955.

The data it needs

station position · ordinal · 31-ft stations
measured value · quantitative · inches (middle ordinate on a 62-ft chord)
proposed fitted value · quantitative · inches
elevation secondary value, fitted the same way · quantitative · inches

Built in 6 steps, as its maker described

p. 130, unnumbered figure and 'Table of Measurements'

Skeleton drawing, not the original plate

16 other forms share this skeleton

Source

Church 1915, A Graphical Method of String-Lining Curves, Railway Age

Attribution checked against the source

Searches, not citations

archive.org commons.wikimedia.org scholar.google.com