156 Electric Lighting. [February, 
metal, which effeCt a kind of eleCtric convention, known as 
the disruptive discharge ; and that the more brilliant arc 
between the carbon points is simply due to the use of a sub- 
stance which breaks up more readily, and gives a longer, 
broader, and more continuous stream of incandescent con- 
vention particles. 
This is now readily accepted, but at that time was only 
dawning upon the understanding of electricians. I am satis- 
fied that Mr. Starr worked out the principle quite originally. 
He therefore concluded that, the light being due to solid 
particles heated by eleCtric disturbance, it would be more 
advantageous — as regards steadiness, economy, and simpli- 
city — to place in the current a continuous solid barrier, which 
should present sufficient resistance to its passage to become 
bodily incandescent without disruption. 
This was the essence of the invention specified in King’s 
Patent as “ a communication from abroad,” which claims 
the use of continuous metallic and carbon conductors, in- 
tensely heated by the passage of a current of electricity, for 
the purposes of illumination. 
The metal selected was platinum, which, as the specifi- 
cation states, “ though not so infusible as iridium, has but 
little affinity for oxygen, and offers a great resistance to the 
passage of the current.” The form of thin sheets known 
by the name of leaf-platinum is described as preferable. 
These to be rolled between sheets of copper in order to 
secure uniformity, and to be carefully cut in strips of equal 
width, and with a clean edge, in order that one part may 
not be fused before the other parts have obtained a suffi- 
ciently high temperature to produce a brilliant light. This 
strip to be suspended between forceps. 
I need not describe the arrangement for regulating the 
distance between the forceps, for directing the current, &c., 
as we soon learned that this part of the invention was of no 
practical value, on account of the narrow margin between 
efficient incandescence and the fusion of the platinum. 
The experiments with the large battery that I made — con- 
sisting of 100 Daniell cells, with 2 square feet of working 
surface of each element in each cell, and the copper-plates 
about f of an inch distant from the zinc — satisfied all con- 
cerned that neither platinum nor any available alloy of 
platinum and iridium could be relied upon ; especially when 
the grand idea of subdividing the light by interposing several 
platinum strips in the same circuit, and working with a 
proportionally high power, was carried out. 
