Posted by John Lambert on March 09, 2012 at 22:07:23 user John.
In Reply to: Re: What should we assume? posted by Adam Quinan on March 07, 2012 at 06:30:54:
On my honeymoon many years ago, my wife and I visited a lighthouse near Vancouver Island. The lighthouse keeper showed us over his domain and I was astonished to see what produced the light visble for miles. The light was produced by a simple 40 watt light bulb surrounded by Fresnel lenses which somehow magnified the light. I'm still impressed by the simplicity and the efficiency of the setup.