holes drilled in the lower brass ring supporting the glass. Landau's lamp The lamp is in part a development of the Geordie. Air enters into a ring near the base which is protected by gauze or perforated plate. The air passes down the side of the lamp passing through a series of gauze covered holes and enters the base through another yet another series of gauze covered holes. Any attempt to unscrew the base causes the lever (shown at f in the illustration) to extinguish the flame. The gauze covered holes and passageways restrict the flow to that required for combustion, so if any part of the oxygen is replaced by firedamp, then the flame is extinguished for want of oxidant. The upper portion of the lamp uses a chimney like Mueseler and Morgan lamps. The rising gases pass up the chimney and through a gauze. At the top of the chimney a dished reflector diverts the gases out sideways through a number of holes in the chimney. The gases then start to rise up the intermediate chimney before exiting through another gauze. Gas finally passes down between the outermost chimney and the intermediate chimney, exiting a little above the glass. The outer chimney is therefore effectively a shield. Yates' lamp The Yates lamp is a development of the Clanny. Air enters through the lower part of the gauze top and leaves through the upper part; there is no chimney. The lower glass part of the lamp has seen some development however. It is replaced by a silvered reflector having a strong lens or bull's-eye in it to allow the light out. The result was a claimed 20 fold improvement in lighting over the Davy. Yates claimed "the temptation to expose the flame to obtain more light is removed". The base also contained an interlocking mechanism to ensure that the wick was lowered and the lamp extinguished by any attempt to open it. The lamp was "much more expensive than the forms of lamp now in general use, but Mr, Yates states that the saving of oil effected by its use will in one year pay the additional cost". Evan Thomas The lamp devised and manufactured by Evan Thomas of Aberdare is similar to a shielded Clanny, but there is a brass cylinder outside the gauze above the glass. It resists draughts well but the flame is dull. Morgan The