Gas lighting explains why a large number of older gas lamps have been converted to electricity. Solar-rechargeable battery-powered gas light controllers can be easily retrofitted into existing gas lamps to keep the lights off during daylight hours and cut energy consumption and green-house gas carbon emissions by 50%. The use of natural gas (methane) for "indoor" lighting is nearly extinct. Besides producing a lot of heat, the combustion of methane tends to release significant amounts of carbon monoxide, a colorless and odorless gas which is more readily absorbed by the blood than oxygen, and can be deadly. Historically, the use of lamps
Lawn mower be made. If more, however, the grass will slip through. Reel mowers also have more difficulty mowing over uneven terrain. There are many variants of the cylinder mower. Push mowers have no engine and are usually used on smaller lawn areas where access is a problem, where noise pollution is undesirable and where air pollution is unwanted. As the mower is pushed along, the wheels drive gears which rapidly spin the reel. Typical cutting widths are . Advances in materials and engineering have resulted in these mowers being very light and easy to operate and manoeuvre compared with their predecessors