When a candle burns in an inclined position, most part of the flame rises perpendicularly from the upper side of the wick, and when viewed in a certain direction, it appears in the form of an obtuse angled triangle. And as the end of the wick projects beyond the flame at the obtuse angle, it meets with the air, and is completely burnt to ashes: hence it is rendered incapable of acting as a conductor to carry off part of the combustible matter in the form of smoke. By this spontaneous mode of snuffing, that part of the wick which is acted upon by the flame continues of the same length, and the flame itself very nearly of the same strength and magnitude[8].
[8] The wick’s not being uniformly twisted throughout, may occasion a little variation in the dimensions of the flame.
The advantages which may be derived from candles that require no snuffing and afford no smoke, may be readily understood; but these candles have another property which ought not to be passed over in silence. A candle snuffed by an instrument gives a very fluctuating light, which, in viewing near objects is highly injurious to the eye; and this is an inconvenience which no shade can remove. But when a candle is snuffed spontaneously, it gives a light so perfectly steady and so uniformly bright, that the adjustments of the eye remain at rest, and distinct vision is performed without pain, and without uneasiness.
Candles, on which Mr. WALKER has made experiments, are described in the following
+-----+--------------+---------+---------------+ | |No. of candles| | No. of single | | No. | to the pound |Length in|threads of fine| | | avoirdupoise | inches. | cotton in the | | | weight. | | wick. | +-----+--------------+---------+---------------+ | 1 | 14 | 8.5 | 10 | | 2 | 13 | 9. | 12 | | 3 | 10 | 9.74 | 14 | | 4 | 8 | 10. | 20 | | 5 | 6 | 10.25 | 24 | |Mould| 6 | 13. | | +-----+--------------+---------+---------------+
Number 1, 2, and 3. These candles, when lighted and placed to form an angle of 30° with the perpendicular, require no snuffing: they give lights which are nearly equal, and combustion proceeds so regularly, that no part of the melted tallow escapes unconsumed, except from accidental causes.