The Werdermann regulator is on an entirely new plan; but it has not yet been submitted to the test of practical working outside the laboratory. The positive carbon, which is lowest, ends in a sharp point, which strangely enough retains its figure, while the carbon burns away at the rate of about two inches per hour. The negative carbon is a block having its under side, against which the positive carbon presses, slightly convex. The positive carbon is pressed steadily against the negative by the action of a weight. The increased resistance to the passage of the current, at the sharp point of the positive carbon, generates sufficient heat to produce a powerful light. The light resembles a steadily radiant star, but 'with all its softness and purity of tint, it is so intense, that adjacent gas-flames are thrown on the wall as transparent shadows.' The light will last for fifteen hours without attention, the positive carbon rod being used in lengths of three feet. The carbon block hardly undergoes any change. When the lamp has been burning a long time, a slight depression can be seen at the place where the positive carbon touches it, but by shifting the carbon in its holder this is easily remedied. Mr. Werdermann lately exhibited a row of ten small lamps burning side by side at the same time. 'The two wires from the machine,' says Mr. Hepworth, were carried one on either side of this row of lamps, branch wires being led from them for the service of each lamp. Mr. Werdermann says that his perfected lamps will be furnished with keys, by which the current can be turned on or off, as in the case of gas. We may say in fact, that in the nature of its connections and various arrangements, it ("the Werdermann lamp") most nearly comes up in convenience to the use of gas.' We do not yet know certainly what arrangement Mr. Edison employs to obtain the light of which so much has been heard. It is asserted that his light is obtained from the incandescence of an alloy of iridium and platinum, which will bear without fusion a heat[26] of 5,000 degrees Fahrenheit. It would be unsafe, however, to assume that this account is trustworthy, or to infer (as we might in the case of almost any other inventor), that such being the nature of his plan, it could lead to no result of practical value. As has been well remarked by a contemporary writer, whatever Edison's invention may be, 'it is certain to be something to command respect, even if it does not quite come up to the glowing accounts which have reached us in advance.'