PARK LIGHTING 811 



6. Arrangement of lights (staggered or parallel). 



7. Height of mounting. 



8. Intensity of illumination. 



9. Distribution of light: 

 Horizontal plane. 



(a) Reflectors. 



(b) Symmetric refractors. 

 (<:) Asymmetric refractors. 



Vertical plane. 

 (a] Free light. 

 (&) Reflector. 

 (c} Refractors. 



10. Type of standards and glassware. 



The intensity required for playground illumination is entirely depend- 

 ent upon the demands of the activities to be carried on, whereas the inten- 

 sity required for park lighting will be the minimum which will permit 

 discrimination of objects. 



The uniformity of light desired is a disputed question, some preferring 

 an illumination sufficiently uniform to almost dispense with shadows, 

 whereas others claim that good lighting is dependent upon shadows and 

 silhouettes. 



Intensity, uniformity and absence of glare are matters that can be 

 measured, but the final decision is dependent upon the human equation 

 and the resultant effect on the public in general. 



The following conclusions were reached after a number of these 

 investigations: 



1. Large lighting units of sufficient mounting height to avoid exces- 

 sive glare and spaced as far apart as is consistent with the intensity and 

 uniformity desired are more efficient, more economical and more desirable 

 than many small, low-mounted units placed close together. 



2. That i,ooo-candle power lamps approximately 23 feet high and 

 spaced 200 feet apart produced the most satisfactory illumination for a 

 parkway of straight alignment, provided interference of shade trees could 

 be avoided. 



3. That asymmetric refraction was desirable. 



4. That for the conditions of a test to be made on our own park sys- 

 tem, where the fixed factors which will govern this ultimate selection pre- 

 vail, the lights should be mounted approximately 21 feet high, at spacing 

 of approximately 165 feet, so as to conform to intersection requirements; 

 the lights should hang over the edge of the roadway so as to clearly define 

 the curbs; and that various types of light and refracting glassware should 



