A World-Hunt For Filament Material - 7

A World-Hunt For Filament Material - 7

 Although Edison had instituted such a costly and exhaustive search throughout the world

for the most perfect of natural fibres, he did not necessarily feel committed for all time to

the exclusive use of that material for his lamp filaments. While these explorations were in

progress, as indeed long before, he had given much thought to the production of some

artificial compound that would embrace not only the required homogeneity, but also

many other qualifications necessary for the manufacture of an improved type of lamp

which had become desirable by reason of the rapid adoption of his lighting system.

At the very time Mr. McGowan was making his explorations deep in South America, and

Mr. Ricalton his swift trip around the world, Edison, after much investigation and

experiment, had produced a compound which promised better results than bamboo fibres.

After some changes dictated by experience, this artificial filament was adopted in the

manufacture of lamps. No radical change was immediately made, however, but the

product of the lamp factory was gradually changed over, during the course of a few years,

from the use of bamboo to the "squirted" filament, as the new material was called. An

artificial compound of one kind or another has indeed been universally adopted for the

purpose by all manufacturers; hence the incandescing conductors in all carbon-filament

lamps of the present day are made in that way. The fact remains, however, that for nearly

nine years all Edison lamps (many millions in the aggregate) were made with bamboo

filaments, and many of them for several years after that, until bamboo was finally

abandoned in the early nineties, except for use in a few special types which were so made

until about the end of 1908. The last few years have witnessed a remarkable advance in

the manufacture of incandescent lamps in the substitution of metallic filaments for those

of carbon. It will be remembered that many of the earlier experiments were based on the

use of strips of platinum; while other rare metals were the subject of casual trial. No real

success was attained in that direction, and for many years the carbon-filament lamp

reigned supreme. During the last four or five years lamps with filaments made from

tantalum and tungsten have been produced and placed on the market with great success,

and are now largely used. Their price is still very high, however, as compared with that of

the carbon lamp, which has been vastly improved in methods of construction, and whose

average price of fifteen cents is only one-tenth of what it was when Edison first brought it

out.

With the close of Mr. McGowan's and Mr. Ricalton's expeditions, there ended the historic

world-hunt for natural fibres. From start to finish the investigations and searches made by

Edison himself, and carried on by others under his direction, are remarkable not only

from the fact that they entailed a total expenditure of about $100,000, (disbursed under

his supervision by Mr. Upton), but also because of their unique inception and

thoroughness they illustrate one of the strongest traits of his character--an invincible

determination to leave no stone unturned to acquire that which he believes to be in

existence, and which, when found, will answer the purpose that he has in mind.