The poltergeist was not active when the investigators were present – a common observance in poltergeist cases. A list of poltergeist activity that took place the day before the investigators arrived.
See: “The House of Knocks and Bumps”, pg. 8, pg. 1, pg. 2
Manuscript, “The House of Knocks and Bumps,” Daniel Lehmann, pg. 7, Folder “Baltimore Poltergeist,” Box D, Eileen J. Garrett Parapsychology Foundation collection, Collection 331, Special Collections, University of Maryland, Baltimore County (Baltimore, MD).