Abstract: A method of manufacturing a low-pressure mercury vapor discharge lamp with a discharge vessel comprising two or more substantially parallel co-extending glass discharge tube portions (4 and 5) interconnected through a coupling which extend transversely to the wall of said tube portions. First, the inner wall of an elongate tube is provided with a luminescent material. Then, while heating at least a short zone of the wall, the elongate tube is then divided into two portions. End walls are formed during the division on which the luminescent layer extends the thickness of the tube wall and the temperature of the heated zone are chosen so that no particles of the luminescent material are enclosed in the glass of the end wall during said dividing process and fracture is avoided at least after cooling.At least at the area of the transition from the end wall to the tube wall, the ratio AB/CD is 0.4 to 0.8.

Abstract: Method of producing a low-pressure mercury vapor discharge lamp consisting of two or more parallel discharge tubes which are interconnected by means of a cross-connection. In this method two adjacent discharge tubes are interconnected after the inside of the wall of the tubes has been coated with a luminescent layer and after they have been sealed at one end. The connection between the two tubes is then effected by making an aperture with an outwardly extending collar in the wall of each of the tubes, placing the apertures opposite to one another and fusing the collars together.