Editing Inclinometer (section)

==History==
[[Image:Well's Clinometer - Project Gutenberg eText 19465.png|thumb|The Well's clinometer]]
Inclinometers include examples such as Well's in-clinometer, the essential parts of which are a flat side, or base, on which it stands, and a hollow disc just half filled with some heavy liquid. The glass face of the disc is surrounded by a graduated scale that marks the angle at which the surface of the liquid stands, with reference to the flat base. The zero line is parallel to the base, and when the liquid stands on that line, the flat side is horizontal; the 90 degree is perpendicular to the base, and when the liquid stands on that line, the flat side is perpendicular or plumb. Intervening angles are marked, and, with the aid of simple [[conversion tables]], the instrument indicates the rate of fall per set distance of horizontal measurement, and set distance of the sloping line.

[[Al-Biruni]], a Persian polymath, once wanted to measure the height of the sun. He lacked the necessary equipment to measure this height. He was forced to create a calibrated arc on the back of a counting board, which he then used as a makeshift quadrant with the help of a plumb line. He determined the location's latitude using the measurements taken with this rudimentary tool. This quadrant was most likely an inclinometer based on the quarter-circle panel.<ref>{{Cite journal |last=Carolina Sparavigna |first=Amelia |date=2013 |title=The Science of Al-Biruni |url=http://www.ijsciences.com/pub/article/364 |journal=International Journal of Sciences |language=en |volume=-1 |issue=12 |pages=52–60 |doi=10.18483/ijSci.364 |s2cid=119230163 |issn=2305-3925|arxiv=1312.7288 }}</ref>

The [[Abney level]] is a handheld [[surveying]] instrument developed in the 1870s that includes a sighting tube and inclinometer, arranged so that the surveyor may align the sighting tube (and its [[crosshair]]) with the reflection of the bubble in the [[spirit level]] of the inclinometer when the line of sight is at the angle set on the inclinometer.

One of the more famous inclinometer installations was on the panel of the Ryan NYP "[[The Spirit of St. Louis]]" aircraft built for the first nonstop transatlantic flight—in 1927 [[Charles Lindbergh]] chose the lightweight Rieker Inc P-1057 Degree Inclinometer<ref>{{cite web|url=http://www.riekerinc.com/M-Inclinometer/ryan_nyp_spirit_of_st.htm|title=Rieker Inc P-1057 Degree Inclinometer|website=riekerinc.com|access-date=7 April 2018}}</ref>{{npsn|date=March 2025}} to give him climb and descent angle information.