308 ROUGH WAYS MADE SMOOTH. 



a glass shade which will be suitable for a light thus changing 

 in position. 



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 posi- 

 tive carbon touches it, but by shitting 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. Hep- 

 worth, '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 con- 

 venience 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 he^rd. It is asserted that his light is obtained from 

 the incandescence of aa alloy of iridium and platinum, 



