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The Stem Press

 

Evolution of the Stem Press

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
1879

Early round seal "Petticoat" press showing glass tubes on inner leads. Screw clamps connect inner leads to filament
1880

Early round stem with no glass tubes, "Smooth" press, screw clamps connect inner leads to filament.
1880

Flat seal stem with long platinum inner leads connecting to screw clamps.
1880

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

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

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

 

Flat seal stem, platinum reduced to a minimum.
1890

Later type with  copper tips omitted and platinum leads run through the seal, but with remaining welds still embedded in the glass
1894

   

Other Unusual and Early Stems, Clamps, and Presses

 

 

Weston w/ Tamadine filament
1885

 

Perkins-Mather carbonized paper hairpin filament


 

Perkins-Mather spiral filament
 

Maxim
1880

Perkins-Mather multi-filament
1880

 


Packard 32cp Lamp, Thomson-Houston base

   

 


 


 

 

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