Illustration: The light intensity of the Davy lamp is only 1/5 of a candle.
Soon after the introduction of the Davy lamp, the initial enthusiasm gave way to disappointment. The Davy lamp did improve safety, but it had a significant drawback: due to the fairly dense mesh cage, the light output was very low, only one-fifth of that of an ordinary candle. During "shifts" (working hours), the light output even dropped by half (Gales 1993: 21).
The miners were not happy with this, especially when working in less gas-rich mines. They had difficulty spotting loose rocks because the lamp emitted only one-fifth of the usual light. Moreover, the light didn’t shine upwards due to the cover. It was also not allowed to tilt the lamp, as this would cause the flame to touch the mesh, causing it to glow. As a result of the introduction of the Davy lamp, accidents involving falling rocks and coal clearly increased (Hubig 1983: 29).
(Gales, B.P.A.: Delfstoffen, Machine- en Scheepsbouw. Mijnbouw, Machinebouw. Scheepsbouw. In: Geschiedenis van de techniek in Nederland. De wording van een moderne samenleving 1800-1890. Deel IV. Delfstoffen, machine- en scheepsbouw. Stoom. Chemie. Telegrafie en telefonie, 1993, p. 21)
(Hubig, Peter: 160 Jahre Wetterlampen, Essen, 1983, p. 29)