FURTHER ILLUSTRATIONS OF THE MODE OF COMPUTING THE RELATIVE COST OR VALUE OF LIGHT, EMITTED BY MEANS OF CANDLES, LAMPS, & OTHER BODIES. It is sufficiently known that the light of a candle, which is so exceedingly brilliant when first snuffed, is very speedily diminished to one-half and is usually not more than one-fifth or one-sixth before the uneasiness of the eye induces us to snuff it.[5] Whence it follows, that if candles could be made so as not to require snuffing, the average quantity of light afforded by the same quantity of combustible matter would be more than doubled. [5] Ezekiel Walker.--Nicholson’s Journal, Vol. IV. 8vo. Series. When a lighted candle is so placed as neither to require snuffing or produce smoke, it is reasonable to conclude that the whole of the combustible matter which is consumed is converted to the purpose of generating light; and that the intensities of light afforded in a given time, by candles of different dimensions, are in proportion to the quantity of matter consumed. That is to say; when candles are made of the same materials, if one candle produce twice as much light as another, the former will in the same time lose twice as much weight as the latter. To prove the truth of this position, Mr. Walker made the experiments contained in the following TABLE. +-----------+--------+--------+----------+--------+---------+ | | | | Weight | | | | | | | of the | |Distance | | No. of | No. of |Time of | Candles |Strength| of the | | the | the |burning.| consumed | of | Candles | |Experiment.|Candles.| | in a | Light. |from the | | | | | given | | Wall. | | | | | time. | | | +-----------+--------+--------+----------+--------+---------+ | | | h. | oz. dr. | | Feet. | | {| 1 | 3 0 | 0 15 | 1 | 7 | | 1 {| 3 | 3 0 | 1 1½ | 1 + | 7 | | {| Mould | 3 0 | 0 15 | 1 | 7 | +-----------+--------+--------+----------+--------+---------+ | {| 1 | 2 55 | 0 15 | 1 | 8 | | 2 {| 3 | 2 55 | 1 0 | 1 + | 8 | | {| Mould | 2 55 | 0 15 | 1 | 8 | +-----------+--------+--------+----------+--------+---------+ | {| 1 | 3 0 | 0 15¾ | 1 | 8 | | 3 {| 3 | 3 0 | 1 2 | 1⅛ | 8¾ | | {| Mould | 3 0 | 0 0 | 1 | 9 | +-----------+--------+--------+----------+--------+---------+ | 4 {| 5 | 3 0 | 1 5 | 1.18 | 8¾ | | {| Mould | 3 0 | 1 1⅛ | 1. | 8 | +-----------+--------+--------+----------+--------+---------+