190 ANNUAL REPORT SMITHSONIAN INSTITUTION, 19 3 9 



envisaged the modern applications or developments; this has been 

 the work of engineers and chemists. But without the work of investi- 

 gators in pure science the engineers would have no knowledge to apply. 



That atomic research is the most profitable avenue of investigation 

 of nature and its results the most useful tools for our control over 

 our environment is very clearly brought out by looking briefly at the 

 results that have been achieved. Our first quantitative knowledge 

 of the atomic nature of matter, sketchy and imperfect as it was, can 

 be attributed to Dalton at the beginning of the last century. The 

 laws of the ordered proportions in which elements combine to form 

 compounds pointed unequivocally to this hypothesis. It is from this 

 advance more than any other that the modern science of chemistry 

 is due. Dalton never dreamed of what the modern chemist can do 

 with petroleum, coal tar, and cellulose but without the hypotheses 

 associated with his name and those of his successors we would not 

 have the fuel, power, the means of transportation, or the synthetic 

 materials that make our lives more comfortable, painless, and effective 

 than those of any other age. At this stage of development chemistry 

 begins to branch away from the main trunk of natural philosophy 

 which is physics. The ramifications of chemistry are too numerous 

 for our further consideration, and we shall confine our attention to 

 those results of Dalton's theory that are more immediately related 

 to the later discoveries of atomic research. 



The developments of the past century were based largely on 

 hypothesis of the discrete granular structure of matter, but with the 

 beginning of this century we have entered on a more detailed under- 

 standing of the properties and characteristics of these atoms in differ- 

 ent states of agglomeration and of the actual submicroscopic struc- 

 ture of these material units. The results of these pure scientific 

 investigations have completely changed our material civilization 

 within the past 30 or 40 years. In our homes we have incandescent 

 and glow-discharge lamps, and the latter are merely at the begin- 

 ning of their development. We have electric heat and artificial sun- 

 light. We have communication with almost every place in the world 

 by telephone, and the radio is an unparalleled disseminator of news 

 and a source of information and entertainment. We have the com- 

 bination of sound and moving pictures, and television which is still 

 in its infancy. The power and communication industries would not 

 exist as we know them without atomic research. The strength of 

 large structures could not be tested without X-rays, and the electron 

 microscope is just beginning to be applied to metallurgical and bio- 

 logical problems. In medicine atomic research has provided sources 

 of radiation for local heating. X-ray photography and the treatment 

 of disease by the entire spectrum of radiation from the infrared 

 through the ultraviolet to X-rays and radium. This has all occurred 



