Human Environment

A mechanical device used to elevate the axle of vehicle so that one tire is raised off the ground, enabling one to access and change the tire. Most cars have a relatively small, manual jack stored in the same compartment as the spare tire. Professional mechanics often use a larger, hydraulic jack, and in commercial car garages there are often electric pallets that lift the whole car for complete access to all four wheels at the same time, as well as to the underside of the car's body.

Also spelled hand axe. In modern times, a hand ax is a short-handled metal tool with a sharp head used for chopping objects, such branches, trees, or even limbs of an enemy or animal. In prehistoric times, these tools were made of stone and are known by archaeologists as bifaces, as the stone head had been worked on both sides.

A piece of tissue that connects muscles and bones. When a muscle contracts, it actually pulls on the tendon, which in turns pulls on the bone to which it is attached. The muscular contraction, coupled with the associated tug on the tendon and bone, causes the joint across which the tendon is stretched to bend.

A feeling or sensation of one's vision whirling, accompanied by disorientation. This can happen in situations when there is no point of visual reference to a horizon line, which the brain uses to establish visual orientation to one's surroundings. Spatial disorientation in this sense often occurs as an expression of motion sickness. General symptoms of vertigo include nausea, vomiting, and faintness.

Also called a dynamo, a generator is a machine that produces electrical power from mechanical power. While the mechanical power can be generated in a number of ways, often a generator uses a gasoline or diesel engine to produce electricity to power other devices. Generators are a common method of generating electricity in remote or undeveloped areas, or when someone wants to remain off the power grid.

A container generally made of either metal or plastic that carries liquids; often used when hiking or camping.

An explosive warhead, propelled by a rocket, that reaches its target by using a guidance system. When a missile is used underwater it is known as a torpedo, and when it is launched from an aircraft it is known as a cruise missile. The rocket can be filled with liquid or solid fuel, while the missile can be armed with a range of materials, including cluster bombs, biological elements, and nuclear warheads.

Electrical engineering is a subfield of engineering that studies and researches electricity, electronics, and electromagnetism and includes system design in areas such as telecommunications, the computer sciences, and broadcasting. Electrical engineers are people who are certified in this subfield, and at minimum, have received a bachelor’s of science in engineering.

A nitroglycerin-based explosive material often used for construction, mining, and demolition. Dynamite was patented in 1867 by Alfred Nobel, a Swedish chemist, and ironically, the inceptor of the Nobel Peace Prize. The name “dynamite” comes from the Ancient Greek work for “power”, δύναμις (dýnamis). Dynamite is composed of earthy materials, such as sawdust, soaked in nitroglycerin, which when exposed to heat can cause a detonation. If left in storage for too long, nitroglycerin can seep from the sawdust into surrounding materials and make the dynamite unstable, thereby causing unexpected explosions. Today, dynamite is wrapped in plastic or a wax-coating to eliminate this risk.

A dry camp is a camp where there is not a nearby source of water, often in remote areas. Dry camping requires that campers carry their own potable water and that they carefully conserve what water they have access to. Dry camping is also often associated with impermanence, as in a dry camp is not a camp in which one stays in for long periods of time, but rather moves through on the way to somewhere else.