Abstract: A compact low-pressure mercury vapour discharge lamp comprises two or more straight tubes which are interconnected at their ends to form one discharge chamber between two electrodes located in the outermost ends of the lamp. These ends are connected in a gas-tight manner to a lamp base incorporating the requisite contact pins and conductors. Down stream of the electrodes in the direction of the discharge current are tube constrictions which define spaces around the electrodes in which released ions from the electrode emission material are held concentrated, so as to fall back onto the electrode surface upon each change in current phase. The invention includes a method including several specific operating parameters, for making the glass envelope of the invention lamp.