| National Biodiversity Network (NBN) |
| The National Biodiversity Network is a project to build the UK's first network of biodiversity information.
www.nbn.org.uk. |
| National Monuments Record (NMR) |
| National Monuments Record. The national repository for archaeological and historic data. |
| National Park |
| These are the most beautiful and dramatically different expanses of country in England, Wales and Scotland. The statutory title recognises their national importance and provides the highest degree of protection for these landscapes. Their designation is for the purposes of conserving their natural beauty, wildlife and human heritage and promoting the understanding and enjoyment of these special qualities. The National Park Authorities are heavily commited to Sustainable Development and this is a thread which runs througout their work. Association of National Park Authorities. |
| National Vegetation Classification (NVC) |
| The National Vegetation Classification was commissioned in 1975 by the former Nature Conservancy Council to provide a comprehensive and systematic catalogue and description of the plant communities of Great Britain. These are published by the JNCC. |
| Natural Frequency |
| Natural Frequency is the frequency at which a body will freely vibrate. Resonance occurs when the natural frequency of a body is equal to the frequency of a periodic force applied to the body, which results in large amplitude oscillations. |
| NBN |
| See National Biodiversity Network. |
| Night-soiling |
| This was the practice of putting sewage and cess on fields as a fertilizer.
|
| NIMBY |
| An acronym which is often used to describe the attitude of objectors or protestors. It means ?Not In My Back Yard? and is often held by those who acknowledge the need for a particular development, but don?t want it near them. |
| Nip angle |
| The angle formed between the fixed and moving crushing surface at which point the material will be pinched, typically applies to jaw, cone and roll crushers, this angle varies with machine size and material lump size. |
| NMR |
| See National Monuments Record. |
| Noise |
| Noise is defined as unwanted sound and is usually measured in dB(A). |
| Noise Equivalent Level |
| See LAeq,T |
| Non-Aquifer |
| See Aquiclude
|
| NVC |
| See National Vegetation Classification. |