Date: ca. 1924-1928
Country of Origin: United States of America
3-D Test: 26 x 10.2cm (10 1/4 x 4 in.)
Overall, glass; wound string around part of tube over a thin cardboard underlay; each smaller tube extension with thin wire strands, apparently copper, imbedded inside each; broken off metal spring inside larger, main tube.
American rocket pioneer Robert Goddard (1882-1945) used this device between 1924 and 1928 in his experiments to determine the feasibility of ion propulsion for space travel. Ion engines, in which electrically charged particles of atoms are discharged, produce extremely high exhaust velocities. Experiments in space with ion propulsion first took place in 1964.
According to a 1964 note written by Russell B. Hastings, one of Goddard's graduate students at the time of the ion experiments, "the tube looks like an early attempt to either singly deflect electrons by a magnetic field or possibly to measure the ratio of charge to mass.... If so this might be a prize piece." Mrs. Goddard gave this artifact to the Smithsonian in 1965 as part of a set of laboratory glassware from her husband's pioneering ion-propulsion experiments.
Gift of Mrs. Robert Goddard