RT Journal Article SR Electronic T1 On the use of planes and knife-edges in pendulums for gravity measurements JF American Journal of Science JO Am J Sci FD American Journal of Science SP 144 OP 150 DO 10.2475/ajs.s3-45.266.144 VO s3-45 IS 266 A1 T. C. Mendenhall YR 1893 UL http://www.ajsonline.org/content/s3-45/266/144.abstract AB