APPLICATIONS TO SUBMARINES 



369 



night, look-out duty, etc. Secondly, most 

 people do not like the harsh, cold appearance 

 of fluorescent light. Human complexion 

 and colored objects look unnatural under 

 many fluorescent tubes (3500° K, 4500° K, 

 6500° K — dayhght) . It must be recognized, 

 however, that Buck and Froehch (3) did 

 find that people preferred soft white fluores- 

 cent light over incandescent. On the other 

 hand, the heat generated and their shape 

 seem to be the main arguments against incan- 

 descent fixtures. Air conditioning should 

 take care of the heat. The quality of 

 incandescent illumination is usually well 

 liked. It may be described as soft and 

 warm, qualities that are comfortable and 

 relaxing to humans. Careful thought and 

 some research should be done on this prob- 

 lem before fluorescent lighting is generally 

 adopted. It should be noted that incandes- 

 cent light fixtures are now available in shapes 

 other than the standard bulb. 



In those compartments where the ceilings 

 are low or predominantly covered by pipes 

 and the like, there should be no attempt to 

 illuminate the ceihng to obtain reflected 

 light, and in addition a low bright ceiling 

 makes an uncomfortable visual environment. 

 Furthermore, the brightest illumination 

 should be at the work surface, not on a low 

 ceiling which should be the least conspicuous 

 place in the room. 



Uniform general lighting in all compart- 

 ments of submarines is impracticable and 

 probably impossible. While best vision re- 

 sults from brightness ratios of three to one 

 or less for adjoining areas in the visual field, 

 ratios as great as ten to one are tolerable. 

 And as pointed out above (13), some con- 

 trast in color and brightness is desirable. 

 Nicely blended shadows increase the attrac- 

 tiveness of a living space. 



In much of the submarine, directional 

 lighting will be found most satisfactory. 

 Any fixtures within the field of view should 

 have dift"using surfaces or louvers so that the 

 surface brightness will be low, i.e., one candle 

 per square inch, or as near this as is possiple. 



What is needed is directional lighting pro- 

 duced by sources of low brightness at nor- 

 mal viewing angles, and of sufficiently low 

 brightness in the "beam" so that specular 

 reflection will not become a problem. The 

 important thing is to avoid glare from fix- 

 tures and to get the right amount of light to 

 places where it is needed, i.e., dial-faces, 

 table and desk tops, etc. Where directional 

 lighting is used, care must be exercised to 

 avoid excessive brightness contrast with ad- 

 joining areas. When directional light is ap- 

 phed to glass covered dial faces, the angle of 

 incidence should be such that the greatest 

 amount of light possible gets through the 

 glass to the dial surface and still have the 

 angle of reflection such that the reflected 

 fight does not shine into the reader's eyes. 

 If practical, it would be desirable to dispense 

 with highly polished surfaces (such as valve 

 handles) to avoid annoying specular reflec- 

 tion. They might be painted, or a dull- 

 appearing metal might be used. 



The amount of light needed will vary with 

 the fineness of the discrimination required. 

 Where scale divisions on dial faces are rela- 

 tively small, where reading of small print or 

 maps is required, where typing is to be done, 

 and where labels in small print are to be per- 

 ceived, the fight should be between 20 and 

 50 foot-candles. Where the discrimination 

 is less severe, 10 to 20 foot-candles will be 

 found adequate. The illumination on any 

 work surface should not drop below 10 foot- 

 candles unless requirements of the situation 

 demand it, e.g., in the conning tower. 



Painting should provide both reflecting 

 surfaces (where possible) and pleasing color 

 combinations. On large areas saturated 

 colors and any paint of low reflectance should 

 be avoided. Tints of colors (pastels) should 

 be used. Ceilings that are exposed so they 

 may act as reflecting surfaces should be near 

 white (perhaps a light cream or ivory) with a 

 reflecting factor of 70 to 80 percent. The 

 paint on instrument panels and bulkheads 

 should reflect 40 to 60 percent, and on table 

 tops and other furniture it should reflect 30 



