by Fred » Thu Jul 23, 2009 3:42 pm
I like the part from the site about candlepower then and now.
"The original definition of a 'standard candle' was:
"A 7/8 inch diameter sperm whale fat candle weighing one-sixth of a pound, burning at the rate of 120 grains per hour."
The modern definition of the candela is:
"the luminous intensity in a given direction of a source that emits monochromatic radiation of frequency 540 x 1012 Hz and that has a radiant intensity in that direction of 1/683 watts per steradian""
Then goes on to five different ways of measuring effective intensity,no wonder us lightkeepers used to get confused,at least using paraffin lights you had a glimmer of an idea what candlepower was when asked how many candlepower is the light?