You do not need a parachute to go skydiving...
You need a parachute to go skydiving twice.
LimelightIn 1825, Thomas Drummond made the first practical use of limelight while surveying in Ireland to enable work through misty days and night. He created an intense light from a lump of lime (calcium oxide) heated to incandescent by an oxygenated alcohol flame in front of a reflector. The haze over Lough Neagh obscured the view between Slieve Snaght, in Donegal, and Divis Mountain 66 miles away near Belfast, but the light penetrated it.* He attempted to adapt it for lighthouses, but found operation too costly. The bright light given off by heated metal oxides was first investigated in the 1820s by Goldsworthy Gurney who created the oxyhydrogen blowpipe. Limelight was also used not only in theatres, but even for microscope illumination.«[Image: theatrical limelight spotlight.] |
