Morgan is a cross between the Mueseler and the Marsaut. It is a shielded lamp with a series of disks at the top to allow spent fumes out and a series of holes lower down the shield to allow air in. There is an inner and outer shield so that air cannot blow directly on the gauze but must first find its way through a slim chamber. There are multiple gauzes, like the Mersaut, and there is an internal chimney like the Mueseler. There is no "shelf" supporting the chimney, instead it hangs from an inverted cone of gauze. The Morgan will resist air up to 53 feet per second and is "sufficiently safe for every practical purpose". Clifford The Clifford also has a double shield, but with a plain flat top. The chimney is quite narrow with gauze covering the top. The bottom of the chimney has a glass bell covering the flame. The chimney is supported on a gauze shelf. Air enters through the lower part of the outer shield, through the passage and into the lamp through the inner shield. It is drawn down through the gauze then passes the flame and ascends the chimney. At the top it leaves through gauze and the top of the double shield. The inner chimney is made of copper coated with a fusible metal. If the lamp gets too hot the metal melts and closes up the air holes, extinguishing the lamp. The lamp has been tested and according to Lupton "successfully resisted every effort to explode it up to a velocity of more than 100 feet per second". Electric lamps It was not until tungsten filaments replaced carbon that a portable electric light became a reality. An early pioneer was Joseph Swan who exhibited his first lamp in Newcastle upon Tyne in 1881 and improved ones in subsequent years. The Royal Commission on Accidents in Mines set up in 1881 carried out extensive tests of all types of lamps and the final report in 1886 noted that there had been good progress made in producing electric lamps giving a light superior to that of oil lamps and expected economic and efficient lamps to become available soon. This turned out not to be the case and progress was slow in attaining reliability and economy. The Sussmann lamp was introduced into Britain in 1893 and following trials at Murton Colliery in