As Anne Pemberton noted in her query, Thomas and Martha Jefferson didn't
have a son; or more accurately their only male child survived only a few
weeks.
  And if I remember the date range correctly, Jefferson himself was long
dead before ingenious Victorians were inventing and marketing the
devices mentioned.
  Social historians have produced a considerable scholarly literature
about the 19th-century hysteria over the alleged medical consequences of
masturbation. Several of these works describe Victorian-era contraptions
designed to prevent "self-abuse." For anyone interested in reading more
about these aspects of medical/social history, the first two books by
Laqueur and Horowitz are probably the best place to start:

Thomas W. Laqueur, Solitary Sex: A Cultural History of Masturbation (New
York, 2003)

Helen Lefkowitz Horowitz, Rereading Sex: Battles over Sexual Knowledge and
Suppression in Nineteenth-Century America (New York, 2002)

Roy Porter, Flesh in the Age of Reason: The Modern Foundations of Body and
Soul (New York, 2003)

Roy Porter and Lesley Hall, The Facts of Life: The Creation of Sexual
Knowledge in Britain, 1650-1950 (New Haven, 1995)

Roy Porter, “Forbidden Pleasures: Enlightenment Literature of Sexual
Advice,” in Paula Bennett and Vernon A. Rosario II, eds., Solitary
Pleasures: The Historical, Literary, and Artistic Discourses of
Autoeroticism (New York, 1995), 75-98.

Alex Comfort, The Anxiety Makers: Some Curious Preoccupations of the
Medical Profession (London, 1967)

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Dr. Jon Kukla, Executive Vice-President
Red Hill - The Patrick Henry National Memorial
1250 Red Hill Road
Brookneal, Virginia 24528
www.redhill.org
Phone 434-376-2044 or 800-514-7463