RT Journal Article SR Electronic T1 A CONSTANT VACUUM APPARATUS JF Science JO Science FD American Association for the Advancement of Science SP 505 OP 506 DO 10.1126/science.100.2605.505-a VO 100 IS 2605 A1 CAMPBELL, JOHN W. A1 BEARD, J. W. YR 1944 UL http://science.sciencemag.org/content/100/2605/505.2.abstract AB