Danville’s magnetic history

A stone marker outside the Hendricks County Historical Museum is a monument to magnetism. The magnetic compass was a powerful invention. The mineral magnetite or “lodestone” was used to magnetize compass needles in China as early as 200 BC. Some say this technology was brought to the West by Marco Polo.

In the 1200s, the compass needle was thought to point to the north star. Around 1600, Sir William Gilbert noted that a splinter of magnetite hung from a thread took up a “generally north-south position” and suggested this was evidence that the Earth has an iron core and acts as a bar magnet.

While the “generally north-south” aspect of a compass was helpful, it was open to improvement. The magnetic compass was helpful for navigation because the previous technology, a sextant, required a visual siting of the sun or stars, preventing its use under overcast skies or on rough seas. Improvement was needed because the magnetic north pole isn’t located at the geographic north pole, and because the location of the magnetic north pole wanders over time.

To address these issues, the United States Coast and Geodetic Survey established a network of reference stations to be used by county surveyors. In 1908, a “Meridian Station” was established in Hendricks County. A monument was carved from Bedford Limestone and placed well away from any magnetic disturbances: “at the county poor farm, about 1 mile east of Danville.” It marked an 800-foot long true meridian where surveyors could calibrate their instruments.

The bearing of the meridian was referenced to the spire of the Christian Church in Danville. A surveyor could set up their instrument at the monument and know the spire was exactly 81 degrees 00.8 minutes west of the meridian. Their magnetic compass could be adjusted accordingly and then taken anywhere in the county to measure true north.

Trouble came around 1927 when the spire was demolished for the construction of a new church. There was also concern about magnetic influences from a power line and a tool house built nearby. In 1943, Mr. Stanley Shartle inspected the station and found it to be “in a most dangerous place” as the area by then was a parking lot for heavy trucks and road machinery. The monument showed “signs of having been abused, without being displaced however.”

In 1997, Mr. Shartle and Mr. Steve Maxwell of the County Engineering Department found the meridian stone had been knocked down and damaged. Mr. Shartle consulted with Mr. Bob Carroll of the Engineering Department and the two made the decision to move the monument to the Hendricks County Historical Museum where it now resides near the main entryway.

Today you can see the monument by navigating to the museum with the compass in your smartphone. It uses magnetic sensors on a microchip to give you an accurate bearing. Or you can follow your smartphone’s map app to “170 S. Washington Street.”