Incandescent lamp seal means

An improved incandescent lamp having a transparent glass envelope which contains a resistive incandescent filament connected to a pair of conductive inlead wires having an average thermal coefficient of expansion in the 0.degree.-300.degree. C. temperature range between about 37.times.10.sup.-7 cm/cm/.degree.C. to about 50.times.10.sup.-7 cm/cm/.degree.C. that are hermetically sealed to the glass envelope, the improvement wherein said inlead wires are joined to larger diameter inlead wires having greater thermal expansion characteristics in the hermetic seal region and the glass envelope comprises a glass composition which consists essentially of oxides in approximate percent by weight 54-71 SiO.sub.2, 12-18 Al.sub.2 O.sub.3, 4-8 CaO, 10-23 BaO, and 0-3 R.sub.2 O wherein R is an alkali metal ion, along with minor amounts of incidental impurities, residual fluxes, and refining agents, such that the aggregate SiO.sub.2 and Al.sub.2 O.sub.3 content lies within the approximate range 73-83 weight percent, the aggregate BaO and CaO content lies within the approximate range 17-30 weight percent and the ratio between BaO weight percent and CaO weight percent lies within the approximate range 2.3 to 3.5 so as to provide improved reboil resistance.