Telescope earliest existing record of a telescope was a 1608 patent submitted to the government in the Netherlands by Middelburg spectacle maker Hans Lippershey for a refracting telescope. The actual inventor is unknown but word of it spread through Europe. [[Galileo Galilei|Galileo]] heard about it and, in 1609, built his own version, and made his telescopic observations of celestial objects. The idea that the [[Objective (optics)|objective]], or light-gathering element, could be a mirror instead of a lens was being investigated soon after the invention of the refracting telescope. The potential advantages of using [[parabolic reflector|parabolic mirrors]]—reduction of [[spherical aberration]] and no
Water supply and sanitation in the Netherlands remaining 40% comes from surface water, mainly in the West where water utilities pump from the Rhine and the Meuse because groundwater is brackish. The government encourages the use of surface water by charging a groundwater abstraction levy. Average municipal water use is among the lowest in developed countries at only 128 litre/capita/day in 2004. 96% of water users are metered and a portion of their bill - typically about one half - is based on actual consumption. Infrastructure. There are 116,000 km of water pipes in the Netherlands. Human Resources. The ten regional water companies had 4,938 full-time equivalent