222 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1937 



ciphers. This is about the number of electrons (the smallest things 

 known) which would be required to fill up the universe to the great- 

 est distances discovered by astronomy, if the electrons could be 

 imagined to be closely packed side by side to fill up this whole space. 

 Yet this number, large as it is, is very small indeed compared with 

 the aggregate factor by which the energy of a voice striking a tele- 

 phone transmitter in San Francisco is amplified by electronic tubes in 

 the process of a long-distance telephone conversation to London. 

 This amplification factor is about 10^^, or unity followed by 256 

 ciphers. If the universe were multiplied in size by the number of 

 times it is larger than an electron, it could still not hold as many 

 electrons as the number of this telephone amplification factor. 



Then, mostly within 10 years or so, has come an active introduction 

 of thermionic devices which are not highly evacuated, but operate 

 with supplementary action of intense ionization of the gas in the tube. 

 First of these were the low-voltage arc rectifiers, like the tungar. 

 Most interesting and versatile are the thyratrons, which permit easy 

 control of powerful currents and machinery, and give a new means of 

 converting alternating into direct current, or vice versa. In this 

 group also are some of the new types of lamps, of high efficiency or 

 special color. 



Not so striking, but equally interesting, have been the useful appli- 

 cations of the photoelectric effect. First was the use of sensitive 

 photoelectric cells to replace the eye or photographic plate in astronom- 

 ical telescopes. Then came sunshine meters, devices to open doors or 

 count people or sort merchandise automatically, or to register the 

 speed and license number of the unwary autoist. Most important 

 thus far are the current-producing mechanisms in the sound-movie 

 apparatus and in television equipment. 



"VMiile, commercially, radio, sound movies, and long-distance teleph- 

 ony are at present of greatest importance, of no less importance, 

 especially to us as scientists, arc the marvelous tools which have been 

 put into our hands for further research in practically every field of 

 science, from phj'^sics and chemistry to psychology and criminology. 



So we see how, within one generation, the electron has been dis- 

 covered and examined, with its aid our intellectual outlook upon the 

 universe has expanded in content and simplified in basic concept, and 

 in its use mankind has the most versatile tool ever utilized. The 

 end of the story is far from told. Every fact or relationship of the 

 electron appears fuzzy with uncertainties when closely examined, for 

 it can truly be said that every discovery discloses a dozen new prob- 

 lems. The field of practical and commercial uses of electronic devices 

 is certainly still largely in its early stages of exploration. 



This story illustrates in vivid manner a number of characteristics 

 of scientific work, some of which I shall simply enumerate: (1) prog- 



