(1) Any amount of vertical clearing. (2) Space or clearing overhead, as in a doorway, etc.
Headstock
(1) A bearing or support for a revolving or moving part of a machine. (2) The part of a lathe, which supports the spindle, which holds and turns the work.
Hearing
A formal procedure, with issues of fact or law to be tried, in which parties have a right to be heard. Similar to a trial with the possibility of a final order. Hearth The stone or floor of a fireplace, which often extends into the room and is either flush with the floor or raised. Hearth Stone 1. The stone that forms the hearth of a fireplace. (2) A soft stone or powdered composition, which is used for cleaning a hearth, steps, etc. Heartshake Disintegration and splitting, which forms across the growth rings of a log whenever rot, exists at the center of the log.
Hearth
That part of the foor directly in front of the fireplace, and the floor inside the fireplace on which the fire is built. It is made of fire-resistant masonry.
Heartwood
The wood of a tree that reaches from the pith (the soft core or center) to the sapwood (where cells have hardened). This wood may contain phenoloic compounds, gums, resins, etc. making it darker and more decay resistant. Redwood is an example of a wood that is used specifically for its durable qualities.
Heat
A form of thermal energy resulting from combustion, chemical reaction, friction, or movement of electricity. As a thermodynamic condition, heat, at a constant pressure, is equal to internal or intrinsic energy plus pressure times volume.
Heat absorbing glass
Window and skylight glass that contains iron to absorb heat, thus reducing the heat transmitted through the glass.
Heat balance
The outdoor temperature at which a building's internal heat gain (from people, lights and machines) is equal to the heat loss through windows, roof and walls.
Heat capacity
The amount of heat necessary to raise the temperature of a given mass one degree. Heat capacity may be calculated by multiplying the mass by the specific heat.
Heat collector
Also referred to as a solar collector or solar panels, it collects heat from the sun, which is turned, into energy that is used most commonly to heat water for the home or pool. There are different forms of collectors.
