322 



National Resources Planning Board 



Tlio development of television processes is receiving 

 very intensive attention in the laboratories, in the 

 expectation of raising its commercial utility. The same 

 may be said of facsimile transmission, to the improve- 

 ment of which, as concerns the quality of received 

 pictures and speed of sending and receiving, the labora- 

 tories are giving active attention. 



Electric Illumination 



^irtificial illumination has been a need of mankind 

 since prehistoric man began to use burning brands for 

 torches. Indeed, demand by mankind for artificial 

 illumination is so great that we may justly refer now to 

 such illumination as a necessity for comfort, conven- 

 ience, and security. The characteristics of electric 

 illumination are of so desirable a nature that its im- 

 portance is outstanding compared with other means 

 for artificial illumination ; and we are indebted to indus- 

 trial research for its development. That is, electric 

 illumination, like electrical communications, is strictly 

 the child of industrial research. 



Arc lamps arranged with individual mechanisms 

 which made many lamps operable in series in constant- 

 current circuits, and incandescent lamps constructed 

 somewhat as at present (i. e., consisting of a hermeti- 

 cally sealed evacuated glass bulb containing a mounted 

 filament of conducting but high-resistance material, and 

 leading-in wires sealed Ln the glass to enable electric 

 current to be carried to the filament), were both origi- 

 nated near the opening of the fourth quarter of the 

 nineteenth century. The arc lamp referred to was the 

 invention of Charles F. Brush and the incandescent 

 lamp the invention of Thomas A. Edison, each one as 

 the consequence of experimental investigation directly 

 aimed at the result ultimately accomplished. Various 

 inventors had preceded Edison and Brush, but had not 

 brought their researches to the point of successful 

 invention. 



Many able men entered the field after the successful 

 inventions were made known, Avdth the result that great 

 laboratory activity grew up and has continued for the 

 improvement of electric illuminating devices. The 

 Brush type of arc lamp has been largely displaced b)' 

 better means for illuminatmg areas for which the earl}^ 

 arc lamps were adapted, and the incandescent lamp 

 has gone through a series of extraordinai-y improve- 

 ments. Collateral research has resulted in additional 

 and special types of electric lamps, such as the so-called 

 mercury-vapor lamp, the neon tube, and fluorescent 

 lamps which are already in considerable use and which 

 hold great promise for future improvements. The 

 result has been to produce safer light, more illiunina- 

 tion for given money expenditure by the users, protec- 

 tion of the eyesight of those who read and study, and 

 greater safety for those who work or move in hazardous 



situations which are not well lighted b}' natural means. 



The researches securing these results arc the joint 

 efforts of physiologists, physicists, chemists, and engi- 

 neers, sometimes working individually, but conunonly 

 worldng in harmonious cooperation. From Mr. Edison's 

 most active days to the present time, industrial re- 

 search laboratories have intensively dealt with the 

 scientific problems of illumination per se and with 

 measures for providing effective illumination by means 

 of devices (lanips) that convert electrical energy into 

 light. 



The outcome of industrial research in the field of 

 ordinary illumination has given us improvements in 

 three categories: 



(1) Improvements obtained through better knowl- 

 edge of the relations of lighting to seeing. Here are 

 problems of physiology and psychology added to prob- 

 lems concerning the arrangements and types of lighting 

 devices, all of which are featm-es of laboratory research. 

 The effects of eye-fatigue, elimination of glare, and the 

 relations of brightness and contrasts all come in, as 

 also do the problems of getting the light where it is 

 most needed. The latter involve investigation of many 

 types of light sources available for use in electric light- 

 ing, their adaptation to specific situations, and the 

 adaptation of reflectors and lenses. 



(2) Safety problems associated with illumination 

 also come into the purview of industrial research, from 

 the results of which du'ections may be formulated for 

 applj'ing light so as to reduce or eliminate hazards where 

 hazards might exist. 



(3) The cost of lamps and of illumination have been 

 notably reduced as an outcome of research, and there- 

 fore the conditions for users have been improved. 



Lamps themselves have been completely revised 

 as the result of research. The carbon filaments of 

 Edison and Swan have changed to filanients of the 

 metal tungsten, and tliis of itself was accomplished 

 only after long and exhaustive research. One problem 

 was to produce from reputedly nonductile timgsten an 

 extremely fine-drawn filament. The highlj' exhausted 

 bulb of Edison has become a bulb still highly exhausted 

 of its ah" but then modified b}^ the introduction of nitro- 

 gen and argon or corresponding special gases. These 

 and other changes of oiu" ordinary incandescent lamps 

 effected as the result of exacting industrial research 

 have brought the lamps to manj' times the efficiency as 

 converters of electrical energy into light as compared 

 with the efficiency of the original Edison lamps of 60 

 years ago. Furthermore, lamps are now made that have 

 individually much greater light output than Edison 

 found it practicable to make even in his later days of 

 lamp manufacture. 



Associated with these changes, research has shown 

 the way to design improved and more accurate proc- 



