562 PLUCKEB ON THE ACTION OP THE MAGNET 



apices, two others, which were terminated below by a triangular 

 plane surface, were screwed in. When these candles, the flames 

 of which were short, were gradually raised higher, the phaeno- 

 mena were exactly the same ; until at last, when the apices of 

 the poles were at about the same height as the centre of the 

 wick, the form corresponding to the fifth figure, its apices, be- 

 coming constantly more depressed, passed into the form of a 

 small very sharply defined boat, the wick representing the mast 

 in the centi'e, from which the sail, which was less luminous 

 than the boat itself, was drawn down, like a tent, towards its 

 edge. 



19. In the experiments with the tallow candle, we made the 

 express condition that it deposited no soot. A very smoky 

 tallow candle exhibits totally different phaenomena. When the 

 two apices of the poles were at three-fourths of the height of 

 the original flame, the equatorial view, given in fig. 6, in which 

 the linear dimensions are reduced to a fourth, was obtained on 

 closing the circuit. The ascending gray smoke, at an elevation 

 of 7 millims., expanded considerably in the equatorial plane. 

 It was sharply bounded externally by a parabola, the summit 

 of which, O, coincided exactly with the middle of the space 

 between the two poles, and retained its regularity for a consider- 

 able time, and as far as an elevation of 190 millims. Internally, 

 the boundary, although tending to the parabolic form, was alter- 

 nately irregular and undulating. More strongly luminous clouds 

 of smoke rotated irregularly from time to time in the internal 

 space. At an elevation of more than 190 millims. the smoke no 

 longer ascended with uniformity, but like a common column of 

 smoke. The flame itself, which was depressed and expanded in 

 the equatorial plane, inclined towards the external boundary of 

 the smoke, at which, becoming parabolically hollowed out and 

 forming apices, it ascended, being sharply defined, and on the 

 outer side also was bounded by a narrow dark gaseous stripe, 

 which at the summit of the flame passed into the column of 

 smoke. 



20. Lastly, I shall allude to the phaenomena presented by a 

 turpentine flame. A narrow lemniscate-shaped wick was spread 

 in the shallow cavity of a porcelain cup ; oil- of turpentine was 

 then poured on it, and it was inflamed. It gave a tolerably 

 steady flame, which emanated from the entire surface of the tur- 

 pentine, and deposited soot abundantly. The apices of the poles 



