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