Vacuum cleaning systems, by M. S. Cooley 70409 [Subtitle: A treatise on the principles and practice of mechanical cleaning] [Author: M. S. Cooley] [Link: https://www.gutenberg.org/7/0/4/0/70409] [Files: 70409-0.txt; 70409-h.htm] Thanks to deaurider, Harry Lamé and the Online Distributed Proofreading Team at https://www.pgdp.net (This file was produced from images generously made available by The Internet Archive) Regards, Al