RT Journal Article SR Electronic T1 The density, rotation and relative age of the planets JF American Journal of Science JO Am J Sci FD American Journal of Science SP 36 OP 56 DO 10.2475/ajs.s2-37.109.36 VO s2-37 IS 109 A1 Gustavus Hinriches YR 1864 UL http://www.ajsonline.org/content/s2-37/109/36.abstract AB