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The Stem Press
Evolution of the Stem Press
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Early round seal stem (called the
"pantaloon" because of it's shape) with long platinum press leads
twisted & soldered to outer leads. Screw clamps connect inner leads to
filament |
Early round seal
"Petticoat" press showing glass tubes on inner leads. Screw clamps
connect inner leads to filament 1880 |
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Early round stem with no glass
tubes, "Smooth" press, screw clamps connect inner leads to filament. |
Flat seal stem with long platinum
inner leads connecting to screw clamps. |
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| Flat seal stem, copper
plated clamps connect platinum press leads to filament. 1881 |
Same as previous
example, but with platinum press leads are made shorter to reduce cost. 1883 |
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| Similar to previous,
but without plaster ring 1884 |
Flat seal stem ,
conductive paste used to attach "goal-post" style inside leads to
filament. Note short base. Edison produced very few lamps with
this configuration. 1885-87 |
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| Flat seal stem,
platinum press leads reduced further 1888 |
Flat seal stem,
platinum reduced significantly by embedding the lead welds inside
the glass seal. 1889 |
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Flat seal stem, platinum reduced to
a minimum. |
Later type with copper tips
omitted and platinum leads run through the seal, but with remaining
welds still embedded in the glass |
Other Unusual and Early Stems, Clamps, and Presses
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Weston w/ Tamadine filament
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Perkins-Mather carbonized paper hairpin filament
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Perkins-Mather spiral filament |
Maxim |
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Perkins-Mather multi-filament
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