"Ancient Astronomical Observations and the Study of the Moon's Motion (1691-1757)" offers a comprehensive analysis of the historical astronomical observations that led to the investigation of the secular acceleration of the Moon. The discovery by Edmond Halley in the late 17th century that the mean motion of the Moon is gradually accelerating sparked renewed interest in ancient astronomical reports. This book is the first detailed study tracing the use of these ancient and medieval observations from Halley to the determination of acceleration by Richard Dunthorne, Tobias Mayer, and Jérôme Lalande in the 1740s and 1750s. It utilizes extensive, previously unstudied manuscripts and demonstrates how different astronomers interpreted the same historical data in various ways. Furthermore, it addresses the broader context of discussions about the secular acceleration of the Moon, including its relevance to biblical chronology and geographical longitudes. This work is aimed at historians of astronomy, astronomers, and historians of antiquity.