To meet the growing demand for efficient lighting UK company Holophane began to manufacture prismatic glass pretty much at the birth of electricity. Prismatic shades operate by breaking up and spreading the beam of light into a myriad of beams using prisms, making a lower voltage bulb a much more effective light source, perfect for the early days of electricity. As a result Holophane lights were frequently used in Curches, as street-lights and to illuminate factories with lights such as this Paint-works light from the 1950's (easy to spot the age due to the degraded aluminium, all the good stuff had been used in WW2)
A fascinating insight into Prismatic lighting. This short film from Holophane entitled The Legend Of The Prism gives a concise history of the famous lighting manufacturer from it's birth in the early 20th Century to the present day. You can even watch the glass being hand-blown as it used to be.
Next time you take a stroll down a street, or find yourself in a railway station have a look up and see if you are lucky enough to spot a Holophane light. There are still some vintage ones in use today- although they are sadly quite rare due to vandalism and many have been replaced with plastic shades which simply do have the same quality of light.