2026-10-06 Wikipedia, "Crookes tube" (tertiary source; used for leads only)

Found [web]

Says Crookes reached 10^-6 to 5 x 10^-8 atm "using an improved Sprengel mercury vacuum pump invented by his coworker Charles A. Gimingham" (sic; the IET obituary gives Charles Henry Gimingham). 5 x 10^-8 atm = 1/20,000,000 atm, matching the lecture's highest vacuum [read: deep read section 7].
Two-theory framing: Crookes and Cromwell Varley ("radiant matter", charged atoms) vs E. Wiedemann, Hertz and Goldstein ("aether vibrations"). Cites Dahl, "Flash of the Cathode Rays" (1997), Thomson 1903, Pais 1986.
Credits the hinged Maltese-cross shadow tube to Julius Plücker in 1869. Note: the lecture attributes its hinged aluminium cross to Mr. Gimingham's construction and shows the "tired glass" effect [read: deep read section 2]; Plücker died in 1868 [memory, high]. The Wikipedia attribution looks doubtful and needs a primary source.
Hertz's failed electrostatic deflection (attributed to poor vacuum) and Schuster's later positive result; Perrin 1895 charge collection; Goldstein 1886 canal rays; Goldstein's failed Doppler-shift search; Lenard window.
Paddle wheel: Thomson 1903 estimated electron momentum would give about one revolution per minute; motion attributed to the radiometric effect.

Claim 4 (negatively electrified): Perrin (1895) and Schuster (electrostatic deflection) are later independent tests of the negative charge. Thomson 1897 shows the carriers are not molecules. All need primary citations (Schuster 1890 Proc. R. Soc.; Perrin 1895 Comptes rendus).
Claim 5: see harvard note.