Recovering rare documents and historical practices of the Time Service of the National Observatory

Abstract

For many years, meridian elbow type transits Bamberg and Askania, both preserved in the Museum of Astronomy and Related Sciences (MAST), were dedicated to the Time Service of the Brazilian National Observatory (ON) in close cooperation with the Bureau International de l’Heure. During the restoration of the Bamberg transit by the MAST team, many numerical spurious symbols scratched on its body and in a small strip of paper behind the level were found in the instrument. Historic documents were examined looking for the meaning and origin of those symbols. Also, laboratory experiments and interviews were made. In addition to those motivating facts the use of that instrument in researches that led to the detection of the non-uniform rotation of the Earth enriches its long history and justifies forward investigations into this object.