Chat*. XX.

GAS LIGHTING.

1231

appeared very desirable to procure a brilliant light, capable of penetrating the almostconstant haze which impeded his observations. lie began his inquiries by repeating someof Berzelius ’s experiments on the distinctive qualities of the different earths before theblow-pipe ; that assigned to lime was the property of emitting, when so heated, a peculiarbright light, and which he found produced one so distinct that every particle of limecould be seen with the naked eye. After this experiment, the idea presented itself, thatif an apparatus could be made, containing a ball sufficiently large, and kept in a state ofintense ignition, its effect, when placed in the focus of a reflector, would exceed that of anylight hitherto used.

After many experiments, the extraordinary intensity, as well as useful application of thislight was detailed in two papers published in the Philosophical Transactions for 1826 and1831 : it was afterwards fitted and adapted to the purposes of a lighthouse; the apparatusconsisting of a lamp, (fig. 1933.), which admitted at the same time through the apertures oand h the two gases, hydrogen and oxygen: they came from separate gasometers, and werenot suffered to mix until they arrived at the small chamber c, of which fig. 1931. is asection; into this chamber the oxygen gas from the inner tube is projected horizontally,through a series of very small apertures, and the hydrogen gas rises vertically throughsimilar apertures at d. The united gases then pass through two or three pieces of wdregauze, placed at e, and being thus thoroughly mixed issue through the two jets against theball, b } fig. 1933. To prevent the wasting of the hall opposite the two jets, and at thesame time to diffuse the heat more equally, it is made to revolve once in a minute, bymeans of a movement placed underneath the plate m, and with that the wire/ carryingthe ball and passing through the stem, is connected : notwithstanding this arrangement, theeffect of the heat is such as gradually to cut a deep groove in the ball, so that at the endof about 45 minutes it becomes necessary to change it; to effect this a wire, ab , (fig. 1930.)passes through the focus of the reflector, and upon it are placed a number of balls, at A,required for any given time ; these, by means of the shears, s, are admitted between theplates, p,p> and hence are permitted to fall, in succession, to the focus, / represents thefocal ball, about two minutes before the change; the ball at g falls into the position i, whereit becomes gradually heated; at the end of that time the curved support, t, moving on apivot, is llifowh into the position represented by the dotted line, by the momentarydescent of the ring r, which receiving an impulse from the weight \V acts upon theextremity u of the support; /falls, but it is prevented from descending more than its own

Fig. 1931.

Fig. 1932.

Fig.1934

Fig. 1930.

DHl'MMOSD’S LIGHT.

diameter by the loop /, and ?, following it, occupies the focus; the support t being imme-diately released, returns by the action of a spring to its former position, retains?, and suffers/to escape through the loop into the cistern. The wire ab, and the support t, revolvetogether, and carry round the focal ball, which is ignited, as in fig. 1930. by the two jets,z,z. These jets, which are movable round the joints d>d, enter through small aperturescut in the sides of the reflector, and arc easily adjusted to the proper distance from the