A spectrum tube for the Balmer series of hydrogen that is simple to construct, reliable, and has a useful life in excess of 1500 hours is described. The intensity of the atomic spectrum of hydrogen is more than adequate for visual work with a grating replica or prism, and under proper conditions would be sufficient for photographic use. The molecular spectrum of hydrogen is of negligible intensity when the tube is properly filled. Full information is given on the construction and filling of the tube.