192 BULLETIN 139, UNITED STATES NATIONAL MUSEUM 



Ancient man wrenched some bark from a tree, made it into a bun- 

 dle, lighted it at the camp fire, and the whole industry was covered. 

 Modern man mines coal, transports it, burns it, steams engines, runs 

 dynamos, gets electricity, regulates it, distributes it, measures it, and 

 leads it into the lamp, using scores of direct or collateral industries 

 and hundreds of inventions in the process. A catalogue of the require- 

 ments of this gigantic congeries of industries, whose ramifications 

 appear to be unlimited, would require the continued effort of many 

 individuals. For ages man merely set the train by which oxygen 

 would combine with carbon at a rate which produced the phenomena 

 of heat whose useful, end term was light. For an enormous span in 

 man's history lighting remained as an art untouched by science, and 

 utilizing only the obvious promptings of nature to the effect that 

 light was one of the results of the combustion of organic and some 

 mineral substances. The group consisting of natural or easiest avail- 

 able minerals used for lighting are carbon minerals, which without 

 refining are of little value except in the case of natural gas. The 

 solids of this class were found suitable for the crude methods of out- 

 door lighting practiced in early times, and the semisohd and fluid 

 members found a limited use in later times, being frequently men- 

 tioned by classical writers. 



The other group consists of organic substances, such as wood, resins, 

 waxes, fats, greases, and oils, which from ancient times were the chief 

 reliance for light. These substances possessed a higher degree of 

 combustibihty and gave less residue of a disagreeable character than 

 substances of the first class. It is evident from experience that a fuel 

 fulfilling the exacting conditions required for lighting can not be 

 derived from this class. It is also true that until the advance in chem- 

 istry reached a high point the first class of substances could not con- 

 tribute as they have done to the science of illumination and in other 

 ways to the welfare of the world. 



A third class marking an important step in advance is remarked 

 in gas, at first collected in a pure state from the laboratory of nature, 

 and later the product of chemical engineering. Natural gas was 

 known to the ancients, but they had no facihties for its practical 

 utilization, and to the Chinese, whose possession of bamboo tubes 

 gave rise to some efforts in conducting and use. Coal gas was also 

 observed to be a by-product of the combustion of soft coal by the 

 earliest users of this fuel. In metal working practiced from quite 

 ancient times the smelters must have observed the accumulation of 

 gases. Nevertheless, by the inexorable law of progress the technical 

 requirements and public needs did not synchronize till the close of 

 the eighteenth century. Still another class of comparatively recent 

 discovery is radium and the radioactive elements. In the research 

 for light these elements have not as yet shown any promise. To use 



