H

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H Aerial

An H aerial is an aerial array comprising a dipole and one reflector.

Habanera

The habanera is a slow Cuban dance.

Haber process

The Haber process (named after Fritz Haber) is an industrial process in which

ammonia is manufactured by direct combination of its elements, nitrogen and

hydrogen. The reaction is carried out at 400-500 degrees centigrade and at 200

atmospheric pressure. The two gases, in the proportions of 1:3 by volume, are

passed over a catalyst of finely divided iron.

Around 10% of the reactants combine, and the unused gases are recycled. The

ammonia is separated by either dissolving in water or cooling to liquid form.

Habitual Criminals Act

The Habitual Criminals Act was passed in 1869 granting powers to the police to

apprehend habitual criminals on suspicion. The objective being to be more

effective in the prevention of crime.

Hackle

A hackle is a board set with sharp steel spikes for combing or pulling out hemp

or flax.

Hackney Carriage

see "Hackney Coach"

Hackney Coach

Hackney Coach is the old name for a Hackney Carriage. They originated in London

in 1625 when there were twenty of them available for hire. During the 19th

century Hackney Coaches gave way to Hackney Cabs, which in turn have evolved

into Hackney Carriages, now commonly called taxis.

Hadley cell

In the atmosphere, a Hadley cell is a vertical circulation of air caused by

convection. The typical Hadley cells occur in the tropics, where hot air over

the equator in the intertropical convergence zone rises, giving the heavy rain

associated with tropical rainforests. In the upper atmosphere this now dry air

then spreads north and south and, cooling, descends in the latitudes of the

tropics, producing the North and South tropical desert belts. After that, the

air is drawn back towards the equator, forming the North-East and South-East

trade winds.

Hadron

In physics, a hadron is a subatomic particle that experiences the strong

nuclear force. Each is made up of two or three indivisible particles called

quarks. The hadrons are grouped into the baryons (protons, neutrons, and

hyperons) and the mesons (particles with masses between those of electrons and

protons).

Hafnium

Hafnium is a silvery metal element with the symbol Hf occurring in zircon and

used in nuclear reactors in the control rods and also used for light-bulb

filaments. It was named in 1923 by the Dutch physicist Dirk Coster and

Hungarian chemist Georg von Hevesy after the city of Copenhagen, where the

element was discovered (Hafnia is Latin for Copenhagen).

Hail

Hail is a precipitation in the form of pellets of ice, known as hailstones. It

is caused by the circulation of moisture in strong convection currents, usually

within cumulonimbus clouds. Water droplets freeze as they are carried upwards.

As the circulation continues, layers of ice are deposited around the droplets

until they become too heavy to be supported by the currents and they fall as a

hailstorm.

Hajj

Hajj is the Muslim pilgrimage to Mecca.

Hakama

A hakama is a Japanese garment like flowing trousers, worn by kendoka, and

dating to the Samurai period.

Half-hitch

The half-hitch is a type of knot.

Half-life

In chemistry, half-life is the length of time required for one-half of a

radioactive substance to disintegrate.

Halide

In chemistry, a halide is a compound composed of two elements, one of which is

a halogen.

Hall Effect

The Hall effect is when a piece of semiconductor material with a current

flowing through it is subjected to a magnetic field a voltage is set up between

the faces of the material which are perpendicular to both the current and the

field. It is caused by the charge carriers present in the semiconductor being

deflected in the magnetic field.

Hallein SBC

Hallein SBC is the leading skibob club of Austria.

Hallmark

A hallmark is an official mark stamped on British gold, silver, and (from 1913)

platinum. Hallmarking was instituted in 1327 by the royal charter of London

Goldsmiths in order to prevent fraud. After 1363, personal marks of

identification were added. Today, tests of metal content are carried out at

authorised assay offices in London, Birmingham, Sheffield, and Edinburgh; each

assay office has its distinguishing mark, to which is added a maker's mark,

date letter, and mark guaranteeing standard.

Halogen

Halogen is a particular group of elements with similar bonding properties.

Halogens

In chemistry, the halogens are a family of elements consisting of flourine,

chlorine, bromine and iodine.

Halon

Halons are organic chemical compounds containing one or two carbon atoms,

together with bromine and other halogens. The most commonly used are halon 1211

(bromochlorodifluoromethane) and halon 1301 (bromotrifluoromethane). The halons

are gases and were widely used in fire extinguishers until they're use was

banned in 1994 because of the damage they cause the ozone layer.

HAM-RPM

HAM-RPM is a knowledge-based conversationalist that reasons with fuzzy

information. It was developed at the University of Hamburg.

Hand

The hand was an English unit of measurement applied to horses and silk. One

hand being four inches applied to horses or 840 yards of silk.

Hand and Foot

Hand and Foot is a North American card game related to Canasta, in which each

player is dealt two sets of cards - the hand, which is played first, and the

foot, which is played when the hand has been used up. There are numerous

variations of this game and no standard rules. The most usual version is for

four players in partnership.

Handshaking

In computing, handshaking refers to hardware or software activity designed to

start or keep two machines or programs in synchronisation as they do protocol.

Hansom Cab

see "Cabriolet"

Harmaline

see "Magenta"

Harmonica

The harmonica was originally a musical instrument consisting of glasses tuned

by regulating the amount of water in them, and played by running a wet finger

around the rim (see copophone). The harmonica was first played by Gluck in

1746. Today the term harmonica refers to a mouth organ played by blowing.

Harmonichord

The harmonichord is a keyed instrument, in which sounds are produced by

friction. It was invented by Thomas Kauffmann in 1810.

Harmonium

The harmonium is a keyed instrument, resembling the accordion, the sounds being

generated by the action of wind upon metallic reeds.

Harmsworth Encyclopaedia

The Harmsworth Encyclopaedia ("Everybody's book of reference") was published

c1910 by The Amalgamated Press Limited and Thomas Nelson and Sons, London in

forty fortnightly parts which could then be bound into eight volumes. It was

contributed to by over 500 contributors including; John Adams, Professor of

Education in the University of London, Professor Bastable of Dublin University

and Alfred William Pollard, Assistant Librarian at the British Museum.

Hartley Oscillator

A Hartley oscillator is a thermionic oscillator comprising a triode with an

oscillatory circuit connected between anode and grid, and inductive coupling

between the anode and grid circuits, via a tapping on the inductive element of

the tuned circuit.

Harvard College

Harvard College is a famous University in Cambridge, Massachusetts. It was

founded by the general court at Boston on the 28th October 1636 and derived its

name from John Harvard of Emmanuel College, Cambridge who bequeathed to it his

library and a sum of money in 1638.

Harvard Graphics

Harvard Graphics by Software Publishing Corporation, is an easy-to-use,

integrated business-presentation program that produces text charts,

organisation charts, and graphs including pie, bar/line, clustered, area,

high-low-close, three-dimensional, stacked bar three dimensional, and scatter

charts. Charts are generated from imported data or data keyed into the program.

Harvard Graphics provides many tools to save time. Speed keys speed up common

functions such as printing and saving a chart. Templates allow you to select

your chart attributes once and use them repeatedly. Chartbooks hold related

templates. An automatic datalink links a Lotus 1-2-3 or compatible spreadsheet

to a chart template. Data in 1-2-3 or Excel spreadsheets can be selected using

range names for speed and convenience. Macros automate data entry or any

repetitive task. A DOS Shell allows access to up to seven other applications

without exiting from Harvard Graphics. Harvard Graphics lets you incorporate

text into charts and annotate them with freeform symbol drawings. A link to

Harvard Graphics Draw Partner gives direct access to drawing tools for

modifying charts. You can edit individual elements of your drawing as well as

pieces of a chart. The program includes hundreds of pre-drawn symbols and icons

to add to your graphics. A built-in spell checker is very useful before

finalising a presentation.

Hashish

Hashish is the resinous form of cannabis.

Hearts

Hearts (Black Maria) is a trick taking card game in which the object is to

avoid winning tricks containing hearts; the queen of spades is even more to be

avoided. The game first appeared at the end of the nineteenth century and is

now popular in various forms in many countries.

Heat-stroke

see "Sunstroke"

Hecatomb

Hecatomb was an ancient sacrifice of a hundred oxen, particularly observed by

the Lacedaemonians when they possessed a hundred cities. The sacrifice was

subsequently reduced to twenty-three oxen and goats and lambs were substituted.

Hectare

The hectare is the metric unit of area equal to 10,000 square meters (2.47

acres), symbol ha.

Helical Aerial

A helical aerial is an aerial array composed of a conductor wound in the form

of a helix, the circumference of each turn being equal to a whole number of

wavelengths.

Heliotropic

Heliotropic is a biological term for plants which turn their stems so as to

expose as much leaf surface to the sunlight as possible.

Helium

Helium is a gaseous element with the symbol He.

Helix

A helix is a circular spiral with all the turns the same diameter.

Helmet

A helmet is an item of clothing designed to protect the head.

Helminthology

Helminthology is the study of worms, or helminths.

Hennin

The hennin was a cornet head-dress in the form of an elongated cone hung with

elaborately arranged veils and worn by women in 15th century England.

Henry

Henry is the unit of inductance. An inductor has an inductance of one henry if

an electro-motive force of one volt is induced when the current changes at the

rate of one ampere per second.

Hepatoscopy

Hepatoscopy is divination by reading the marks on the liver of a slaughtered

animal.

Heptachlor

Heptachlor is a man-made compound that was commonly used by American

exterminators and home owners to control and kill termites, and by farmers to

kill insects in seed grains and on crops. Heptachlor epoxide is an oxidation

product of heptachlor formed by many plants and animals, including people,

after exposure to heptachlor. Heptachlor is present as an impurity in the

pesticide chlordane. However, since late 1978, most uses of heptachlor have

been phased out; the chemical is no longer available to the American general

public, and as of April 1988, heptachlor can no longer be used for the

underground control of termites. Heptachlor is a crystalline solid when it is

pure, and a waxy solid as a technical-grade product. Heptachlor epoxide is a

solid. Heptachlor is soluble in water; heptachlor epoxide is insoluble. As a

pure compound, heptachlor is a light tan solid that smells some-thing like

camphor. Heptachlor is also known as:

1,4,5,6,7,8,8-heptachloro-3a,4,7,7a-tetrahydro-4,7-methanoindene;

heptachlorodi-cyclopentadiene. Heptachlor epoxide is also known as

1,4,5,6,7,8,8-heptachloro- 2,3-epoxy-2,3,3a,7,7a-hexahydro-4,7-methanoindene;

epoxyheptachlor.

Heptode

A heptode is a high-vacuum thermionic valve having seven electrodes, namely an

anode, a cathode and five grids.

Heraldry

Heraldry is the subject of armorial bearings.

Herb

A herb is a plant whose aerial parts do not remain above ground following the

growing season.

Heroin

Heroin is a powerful opiate analgesic.

Heterocyclic compounds

In chemistry, heterocyclic compounds are cyclic compounds in which the ring

system of the molecule contains other elements than carbon.

Heterodyne

Heterodyne is the process whereby two oscillations of different frequencies are

combined to produce other oscillations, and particularly oscillations having a

frequency equal to the difference between the frequencies of the two original

oscillations.

Heuristic Dendral

Heuristic Dendral is an expert system, developed at Stanford University, that

establishes the structure of a molecule given the molecule's atomic formula and

mass spectrogram.

Hexoic Acid

see "Caproic Acid"

Hexyl hydride

see "N-hexane"

Hieroglyphics

Hieroglyphics are signs comprising the picture writing of the ancient Egyptians.

High Tension

High Tension is a comparative term used in electronics to denote high voltages.

Highgate Diving Club

Highgate Diving Club is a diving club in London which was founded in 1928.

Members of the club have represented Great Britain in many Olympic, European

and Commonwealth games. The club fought for the advancement of diving.

HiJaak

Hijaak is a graphics accessory program that lets you convert graphic files from

one format to another. The program captures screen images and graphics data

(both text and data) in CGA, EGA, VGA, ATT, DEB, and Hercules graphics

resolutions, and converts graphic files from one format to another on a variety

of machines including the IBM PC, Macintosh, and Amiga. HiJaak is ideal for

desktop publishing or presentation graphics users who want to move a graphic

image into a document where the formats are incompatible. For example, bringing

a vector-based drawing or CAD picture into a painting package or bringing a Mac

paint image into an IBM paint package.

Himation

An himation was a woollen cloak worn by the ancient Greeks.

Hinterland

Hinterland is a country lying immediately behind a coast, river or frontier.

Hitch and Kick

Hitch and Kick was a form of High Jump popular in the Border Games. The

competitor had to kick an inflated bladder hung from a pulley above him.

Hitless Wonders

see "Chicago White Sox"

Hodometer

A hodometer was an early device for measuring the distance travelled by a

vehicle.

Hoe

A hoe is an instrument for cutting up weeds and loosening the earth in fields

and gardens.

Hog Cholera

see "Swine Fever"

Hogshead

The hogshead was a British measure of tobacco ranging from 12 to 18 cwt and of

liquid, applied to beer being equal to six firkins and to wine 63 gallons.

Hola

Hola is a sort of trick taking game for two or four players, but it is unusual

in that a card can only be beaten by a card of equal value, or by a wild card,

sevens and twos being wild. The object is to capture aces, tens and the last

trick. Hola is a Slavic word meaning "nakedness". Hola may be of Polish origin.

It is closely related to the Czech game Sedma (seven). Hola is for two players,

or four players in fixed partnerships, partners sitting opposite. A standard 52

card pack is used. Aces and tens are worth 10 points each - the other cards

have no value. There are also 10 points for winning the last trick. The object

is to take as many of the available 90 points as possible by winning tricks

containing aces and tens, and winning the last trick. Sevens and twos are wild,

and can be used to capture cards of any rank.

Hole in One

Hole in One is a strong golden ale from the Ash Vine brewery at Frome in

Somerset.

Holophote

The holophote was a form of lamp in which the light was converged and directed

to a particular spot to prevent collisions at sea etc.

Honey

Honey is a sweet syrup made by bees from nectar.

Hooliganism

The term hooliganism derives from Hooley Gang, and has been used since 1900 to

describe street ruffians and rowdiness. It was originally applied chiefly to

the East-end of London, and conferences were held between 1900 and 1902 in

London to try to combat the problem by encouraging clubs and brigades for the

boys.

Horn Books

Horn Books were used in education in England from early times to the 18th

century, and were tablets on which were inscribed the alphabet, the nine digits

and other basic information, and protected by a thin film of transparent horn.

Horse Trials

see "Three-Day Event"

Horsepower

Horsepower is an imperial unit of power, now replaced by the watt. It was first

used by the engineer James Watt, who employed it to compare the power of steam

engines with that of horses. In the UK, one horsepower is equal to 550

foot-pounds per second or 745.7 watts. In the USA this figure has been rounded

to 746 watts, and in the metric system it is 735.5 watts.

Horseshoe Pitching

Horseshoe Pitching is an old English game now popular in the USA in which

people toss horse shoes at a near vertical spike, aiming to encircle the spike

with the shoe, or get it as close as possible.

House

A house is a building for human habitation.

House of Tudor

The House of Tudor was an English dynasty descended on the male side from Owen

Tudor, a Welsh knight who married Catherine, widow of Henry V, and was the

grandfather of Henry VII; and on the female side from Edward III through the

Beauforts and John of Gaunt. The Tudor monarchs were Henry VII, Henry VII,

Edward VI, Mary, and Elizabeth I.

Hoy

A hoy was a small vessel, usually rigged as a sloop, and employed in carrying

goods and passengers short distances coastwise, and sometimes in conveying

goods and people to and from larger vessels and the shore.

Huff

In the game of draughts, if a player in a position to capture an opposing piece

neglects to do so, his opponent may "huff" (remove from the board) the piece

which should have made the capture, if he so wishes to do so.

Humus

Humus is partly decomposed organic matter. Found in soil.

Hundredweight

The hundredweight (cwt) is a unit of measurement of the avoirdupois scale

equivalent to 4 quarters, 112 pounds or 50.8 kilograms.

Hydrate

In chemistry, a hydrate is a compound containing water of crystallisation.

Hydration

In chemistry, hydration is the combination of water and another substance to

produce a single product. It is the opposite of dehydration.

Hydride

In chemistry, a hydride is a compound containing a negatively charged hydrogen,

as in sodium hydride(Na-H).

Hydrocarbon

A hydrocarbon is a chemical containing only hydrogen and carbon.

Hydrocarbons

see "hydrocarbon"

Hydrocyanic Acid

Hydrocyanic Acid (Prussic Acid) was discovered by Scheele in 1782, and first

prepared in a pure state by Gay-Lussac in 1811. It is found in the kernels of

bitter almonds, peaches, apricots, plums, cherries and quinces and various

plants leaves including beech, cherry and laurel. It is one of the most toxic

substances known and is used to prepare cyanide.

Hydrogen

Hydrogen is a non-metallic gaseous element with the symbol H. In its free

gaseous state it is only found in nature in small quantities issuing from

crevices in volcanic districts or near petroleum wells. It exists in

combination everywhere; as a constituent of water, of all plants and animals,

and in numerous minerals, abundantly in coal, petroleum, bitumen, etc., and to

a lesser degree in rocks. The element may be separated from any of its

compounds, but it is usually obtained from water or dilute acids.

Hydrogenation

In chemistry, hydrogenation is a chemical reaction in which hydrogen is added

to a compound.

Hydrolysis

In chemistry, hydrolysis is chemical decomposition by which a compound is

resolved into other compounds by taking up the elements of hydrogen.

Hydroxide

A hydroxide is an inorganic compound containing one or more hydroxyl groups.

Hydroxy-toluene

see "Cresol"

Hydroxybenzene

see "Carbolic Acid"

Hyosophen

see "Phenobarbital"

Hypertonic solution

In chemistry, a hypertonic solution is a solution of higher osmotic pressure

than another with which it is compared.

Hypnosis

Hypnosis was developed in 1843 by Braid, a surgeon of Manchester, from the

study of mesmerism.

Hypo

see "Sodium thiosulphate"