The Argand burner differs from the flat flame burners in that a circular flame is employed.  The air supply is regulated by a cylindrical glass, and this form of burner gives a better service than the flat flame burner, as not only can the supply of gas and air be better adjusted, but the air being slightly warmed by the hot glass adds to the temperature of the flame, which is also increased by radiation from the opposite side of the flame itself.

The chief loss of light in such a burner depends upon the fact that, being circular, the light from the inner surface has to pass through the wall of flame, and careful photometric experiments show that the solid particles present in the flame so reduce its transparency that a loss amounting to about 25 per cent. of light takes place during its transmission.

The height of the flame also must be carefully adjusted to the size of the flame, as too long a chimney, by increasing the air supply unduly, cools, and so lowers the illuminating power of the flame.  Experiments with carbureted water gas gave the following results, with a consumption of 5 cubic feet per hour: 

-----------------------------------------------------
Size of Chimney. | Height of Flame. | Candle Power. |
------------------+------------------+---------------|
6 X 1-7/8     |      2-1/2       |     21        |
7 X 1-7/8     |      2-1/4       |     21.3      |
8 X 1-7/8     |      2-1/8       |     20.8      |
9 X 1-7/8     |      1-7/8       |     18.2      |
------------------+------------------+---------------+

For many years no advance was made upon these forms of burner, but when, ten years ago, it was recognized that anything which cools the flame reduces its value, while anything which increases its temperature raises its illuminating power, then a change took place in the forms of burner in use, and the regenerative burners, introduced by such men as Siemens, Grimston, and Bower, commenced what was really a revolution in gas lighting.

By utilizing the heat contained in the escaping products of combustion to raise the temperature of the gas and air which are to enter into combination in the flame, an enormous increase in the temperature of the solid particles of carbon in the flame is obtained, and a far greater and whiter light is the result.

The Bower lamp, in which (at any rate in the later forms) the flame burns between a downward and an upward current of air, was one of the first produced, and so well has it been kept up to date that it still holds its own; while as types of the “inverted cone” regenerative burner, we may also take the Cromarty and Wenham lights, which have been followed by a host of imitators, and so closely are the original types adhered to that one begins seriously to wonder what the use of the Patent Office really is.