Abstract: A high pressure discharge lamp having an arc tube for operation in a generally horizontal position. The arc tube has a generally cylindrical body with end chambers of continuously reducing cross-section in which respective discharge electrodes are arranged. Press seals sealing the end of the arc tube in a gas tight-manner are offset from the axis of the cylindrical body in a direction normal to the press seals and away from the tip-off. The lower circumferential portion of the cylindrical body is smoothly curving and free of flats and the lower portions of the end chambers are smoothly curving and free of crevices.

Abstract: A method of producing a high pressure discharge lamp arc tube having discharge electrodes extending from respective press seals into opposing end chambers of continuously reducing cross-section. The press seals are positioned offset from the axis of the arc tube in a direction normal to their plane by positioning the lead-through and discharge electrode within the end portion of a length of tube of vitreous material offset from the tube axis by a predetermined distance, heating the end portion of the tube to its softening temperature, and moving opposing press jaws against said end portion in such a manner that the press seal is formed about said lead-through offset in a direction normal to the plane of the press seal and away from the tip-off. The press jaws may include mold portions for accurately forming the end chambers. During pressing, the tube is pressurized with a gas to blow mold the end chambers in the mold portions.