Decker

Decker (pronounced dek-er)

(1) Something (typically a bus, ship, aircraft, bed, sandwich et al), having a specified number of decks, floors, levels, layers and such (used usually in combination with a numerical or other expression indicating the number in the construction (double decker, triple decker, upper decker, five decker etc (sometimes hyphenated).

(2) As “table decker” an employee who “decks” (ie sets or adorns) a table used for entertaining (used also as a “coverer”) (archaic).  The idea lives on in the verb “bedeck” (to adorn).

(3) In boxing slang, a fighter with a famously powerful punch, able to “deck” an opponent (ie knock them to the canvas with a single punch).

(4) In historic naval slang, as “quarter-decker”, a label applied to officers known more for their attention to matters of etiquette or trivial regulations than competent seamanship or ability in battle.  It was an allusion to a warship’s “quarter deck” (the part of the spar-deck of a man-of-war (warship) between the poop deck and main-mast (and originally (dating from the 1620s), a smaller deck above the half-deck, covering about a quarter of the vessel’s LOA (length overall)).  In many navies, the quarter-deck was reserved as “a promenade for officers only”.

1785–1795: The construct was deck + -er.  Deck in this context was from the Middle English dekke (covering extending from side to side over part of a ship), from a nautical use of the Middle Dutch decke & dec (roof, covering), from the Middle Dutch decken, from the Proto-Germanic thakam (source also of the noun “thatch” and from the primitive Indo-European root steg & teg- (to cover) and the Old Dutch thecken, from the Proto-West Germanic þakkjan, from the Proto-Germanic þakjaną and related to the German Decke (covering, blanket).  The –er suffix was from the Middle English –er & -ere, from the Old English -ere, from the Proto-Germanic -ārijaz, thought most likely to have been borrowed from the Latin –ārius where, as a suffix, it was used to form adjectives from nouns or numerals.  In English, the –er suffix, when added to a verb, created an agent noun: the person or thing that doing the action indicated by the root verb.   The use in English was reinforced by the synonymous but unrelated Old French –or & -eor (the Anglo-Norman variant -our), from the Latin -ātor & -tor, from the primitive Indo-European -tōr.  When appended to a noun, it created the noun denoting an occupation or describing the person whose occupation is the noun.  The noun double-decker was first used in 1835 of ships with two decks above the water line and this extended to land transport (trains) in 1867.  Decker is a noun & adjective; the noun plural is deckers.

Flight deck of the US Navy's Nimitz-class aircraft carrier USS Carl Vinson (CVN 70).

The reason ships, trains, buses, aircraft and such have "decks" while buildings have "floors” or “stories (or storeys)” is traceable to nautical history and the nomenclature used in shipbuilding.  English picked up “deck” from the Middle Dutch decke & dec (roof, covering) where the use had been influenced by the Old Norse þekja (to cover) and in early shipbuilding, a “deck” was the structure which covered the hull of the ship, providing both a horizontal “working surface” and enclosing the vessel, creating a space for stores, cargo or accommodation which was protected from the elements.  In that sense the first nautical decks acted as a “roof”.  As ships became larger, the nautical architects began to include multiple decks, analogous with the floors of buildings in that they fulfilled a similar function, providing segregated layers (ie the storeys in buildings) used for cannons, crew quarters, storage and such.  As the terminology of shipbuilding became standardized, each deck came to have a specific name depending on its purpose or position (main deck, flight deck, poop deck, gun deck etc).

Ford Mustang convertible (1965–1973) replacement floor pan (complete, part number 3648B) by Moonlight Drive Sheet Metal.

Until the nineteenth century, although the vehicles used on land became larger, they tended to get longer rather than higher but the advent of steam propulsion made possible trains which ran on railways and these could pull carriages carrying freight or passengers.  The first “double decker” versions appeared in France in 1867 and were described as voitures à imperial, (imperial cars) were used on the Chemin de Fer de l'Ouest (Western Railway), the upper deck roofless and thus an “open-air experience”,  Rapidly, the idea spread and double-deck carriages became common for both long-distance and commuter services.  An outlier in the terminology is car design; cars have a floor (sometimes called the “floor pan”) rather than a deck, presumably because there’s only ever one.  In the narrow technical sense there have been cars with “two floors” but they were better understood as a “double-skinned” single floor and they were used for armor or to provide a space for something specialized such as hydrogen fuel-cells, the technique often called “sandwich construction”.

Boeing 314 Clipper flying boat cutaway (left) and front schematics of Boeing 747-300 (right).  Re-using some of an earlier design for a bomber which failed to meet the military’s performance criteria, between 1938-1941, Boeing built twelve 314 Clippers, long-range flying boats with the range to cross both the Atlantic and Pacific oceans.  Although used by the military during World War II, most of their service was with the two commercial operators Pan Am (originally Pan American Airways) and BOAC (British Overseas Airways Corporation).  Very much a machine of the pre-war age, the last Clippers were retired from service between 1946-1948, the advances in aviation and ground infrastructure built during war-time rendering them obsolete and prohibitively expensive to maintain.

Because train designers adopted the nautical terminology, it naturally came to be used also in buses, and aircraft, the term “flight deck” (where the pilot(s) sat) common even before multiple decks appeared on flying boats and other long-distance airframes.  The famous “bubble” of the Boeing 747 (1968-2023) remains one of the best known decks and although most associated with the glamour of first-class international travel, was designed originally as a freight compartment.  The multi-deck evolution continued and the Airbus A380 (2005-2021) was the first “double decker” with two passenger decks extending the full length of the fuselage (with cargo & baggage) carried in the space beneath hence the frequent description of the thing as a “triple decker”.

Lindsay Lohan contemplating three decker sandwich, now usually called a “club sandwich”.  Many menus do specify the number of decks in the clubs.

Deck widely was used of many raised flat surface which people could walk or stand upon (balcony, porch, patio, flat rooftop etc) and came to be used of the floor-like covering of the horizontal sections or compartments, of a ship, a use later extended to land transport (trains, busses etc) and in the twentieth century, to aircraft.  A pack or set of playing cards can be called a deck as (less commonly), can the dealt cards which constitute the “hand” of each player and the notion was extended to sets of just about anything vaguely similar (such as a collection of photographic slides). , Because slides tended to be called a “deck” only when in their magazine, this influenced the later use in IT when certain objects digitally were assemble for storage or use and in audio and video use when cartridges or cassettes were loaded into “tape decks”.  In print journalism, a deck is a headline consisting of one or more full lines of text (applied especially to a sub-headline).  The slang use in the trade of illicit narcotics to describe the folded paper used for distributing drugs was a US regionalism.  There are dozens of idiomatic and other uses of deck, the best known including “all hands on deck”, “swab the decks”, “hit the deck” “clear the decks”, “deck-chair”, “deckhand”, “deck shoes”, “flight deck”, “gun deck”, “observation deck”, “play with a full deck”, “promenade deck”, “re-arranging the deck chairs on the Titanic”, “decked out”, “stack the deck”, “sun deck”, “top deck” & “to deck someone”.

Schematic of the Royal Navy’s HMS Victory, a 104-gun first-rate ship of the line, laid down in 1759 and launched in 1765, most famous as the flagship of Admiral Lord Nelson’s (1758-1805) flagship at the Battle of Trafalgar on 21 October 1805; it was on her Nelson was killed in battle.  Uniquely, after 246 years on the active list, she is the world's oldest naval vessel still in commission.  Although the term wasn’t in use until the 1830s, Victory was a “five decker” configured thus:

Orlop Deck: The lowest deck, mainly used for storage and ship's equipment.
Lower Gun Deck: The deck housing the heaviest cannons.
Middle Gun Deck: This deck contained another set of guns, slightly lighter than those on the lower gun deck.
Upper Gun Deck: The third level of guns, with even lighter cannons.
Quarterdeck and Forecastle: The uppermost decks, where the captain and officers usually directed the ship during battle.

The early meanings in English evolved from “covering” to “platform of a ship” because of the visual similarity and it’s thought the idea of a deck being a “pack of cards” (noted in the 1590s) was based on them being stacked like the decks of a multi-deck man-of-war (warship).  The tape-deck was first so described in 1949 an was a reference to the flat surface of the old reel-to-reel tape recorders.  The first deck chairs were advertised in 1844, an allusion to the use of such thing on the decks of passenger ocean liners and deck shoes were those with sturdy rubber soles suitable for use on slippery surfaces; the modern “boat shoes” are a descendent.  The old admiralty phrase “clear the decks” dated from the days of the tall-masted warships (the best known of which was the big “ship-of-the-line”) and was a reference to the need to remove from the main deck the wreckage resulting from an attack (dislodged masts, sails, spas etc) to enable the battle to be rejoined without the obstructions.  Being made of wood, the ships were hard to sink but highly susceptible to damage, especially to the rigging which, upon fragmentation, tended to fall to the deck.  It may have been a adaptation of the French army slang débarasser le pont (clear the bridge).

Ford 302 cubic inch (4.9 litre) Windsor V8 with the standard deck (left) and the raised deck 351 (5.8) (right).  In production in various displacements between 1961-2000, the 221 (3.6), 255 (4.2), 260 (4.3), 289 (4.7) & 302 (4.9) all used what came retrospectively to be called the “standard deck” while the 351 (5.8) was the sole “raised deck” version.

For decades, it was common for US manufacturers to increase the displacement of their V8 engines but means of creating a “raised deck” version, the process involving raising the height of the engine block's deck surface (the surface where the cylinder heads bolt on).  What this allowed was the use of longer connecting rods while using the original heads and pistons which in combination with a “longer stroke crankshaft” increases the displacement (the aggregate volume of all cylinders).  The industry slang for such things was “decker” and the technique was used with other block configurations but is best known from the use in the 1960s & 1970s for V8s because it’s those which tend to be fetishized.  The path to greater displacement lay either in lengthening the stroke or increasing the bore (or a combination of the two) and while there were general engineering principles (longer stroke=emphasis on more torque at the cost of reducing maximum engine speed and bigger bore=more power and higher engine speeds) but there were limitations in how much a bore could safely be increased including the available metal.  A bigger bore (ie increasing the internal diameter of the cylinder) reduces the thickness of the cylinder walls and if they become too thing, there can be problems with cooling, durability or even the structural integrity of the block.  The piston size also increases which means the weight increases and thus so too does the reciprocating mass, increasing friction, wear and has the potential to compromise reliability, especially at high engine speeds.

Increasing the stroke will usually enhance the torque output, something of greater benefit to most drivers, most of the time than the “top end power” most characteristic of the “big bore” approach.  In street use, most engines spend most time at low or mid-range speed and it’s here a longer stroke tends to produce more torque so it has been a popular approach and the advantage for manufacturers is that creating a “decker” almost always is easier, faster and cheaper than arranging one which will tolerate a bigger bore, something which can demand a new block casting and sometimes changes to the physical assembly line.  With a raised deck, there can be the need to use different intake and exhaust manifolds and some other peripheral components but it’s still usually a cheaper solution than a new block casting.  Ford’s “thinwall” Windsor V8 was one of the longest-serving deckers (although the raised-deck version didn’t see out the platform’s life, the 351 (introduced in 1969) retired in 1997).  Confusingly, during the Windsor era, Ford also produced other 351s which belonged to a different engine family.  Ford didn’t acknowledge the biggest Windsor's raised deck in its designation but when Chrysler released a decker version of the “B Series” big-block V8 (1958-1978), it was designated “RB” (Raised B) and produced between 1959-1979.

1964 AEC Routemaster double decker Bus RM1941 (ALD941B) (left), two sightseeing AEC Routemasters in Christchurch, New Zealand (centre) and one of the "new" Routemasters, London 2023 (right).

London’s red, double-decker busses are one of the symbols most associated with the city and a fixture in literature, art and films needing something with which to capture the verisimilitude.  The classic example of the breed was the long-running AEC Routemaster, designed by the London Transport Board and built by the Associated Equipment Company (AEC) and Park Royal Vehicles.  The Routemaster entered service in 1956 and remained in production until 1968, changed over those years in many details but visually there was such continuity that it takes an expert (and buses are a thing so experts there are) to pick the model year.  They entered service in 1956 and remained in regular service until 2005 although some were retained as “nostalgia pieces” on designated “tourist” routes until COVID-19 finally saw their retirement; since then, many have been repurposed for service around the world on sightseeing duties and other tourist projects.

Boris Johnson (b 1964; UK prime-minister 2019-2022) will leave an extraordinary political legacy which in time may came to be remembered more fondly than it now may appear but one of his most enduring achievements is likely to be the “New Routemaster” which had the typically bureaucratic project name “New Bus for London” but came to be known generally as the “Boris Bus”, the honor accorded by virtue of him championing the idea while serving as Lord Mayor of London (2008-2016).  In truth, the original Routemaster, whatever its period charm, was antiquated years before it was withdrawn from service and although the doorless design made ingress and egress convenient, it was also dangerous and apparently a dozen passenger fatalities annually was not uncommon.  The Borisbus entered service in 2012 and by 2024 almost 1200 were in service.

1930 Lancia Omicron with 2½ deck coachwork and a clerestoried upper windscreen (left) and a “three decker” bus in Pakistan (right).

The Lancia Omicron was a bus chassis produced between 1927-1936; over 600 were built in different wheelbase lengths with both two and three-axle configurations.  Most used Lancia's long-serving, six-cylinder commercial engine but, as early as 1933, some had been equipped with diesel engines which were tested in North Africa where they proved durable and, in the Sudan, Ethiopia, Libya and Algeria, once petrol powered Omicron chassis were being re-powered with diesel power-plants from a variety of manufacturers as late as the 1960s.  Typically of bus use, coachbuilders fabricated many different styles of body but, in addition to the usual single and double deck arrangements, the Omicron is noted for a number of two and a half deck models, the third deck configured usually as a first-class compartment but in at least three which operated in Italy, they were advertised as “smoking rooms”, the implication presumably that the rest of the passenger compartment was smoke-free.  History doesn't record if the bus operators were any more enthusiastic about or successful in enforcing smoking bans than the usual Italian experience.  For a variety of reasons, busses with more than 2.something decks were rare and the Lancias and Alfa Romeos which first emerged in the 1920s were unusual.  However, the famously imaginative and inventive world of Pakistani commerce has produced a genuine “three decker” bus, marketed as the “limousine bus”.  What the designer did was take a long-distance, double decker coach and use the space allocated usually as a luggage compartment to configure as the interior of a long wheelbase (LWB) limousine, thereby creating a “first class” section, the four rows of seating accessible via six car-like (ie limousine) doors.

Mutual & Common

Mutual (pronounced myoo-choo-uhl)

(1) Possessed, experienced, performed, etc by each of two or more with respect to the other; reciprocal.

(2) Having the same relation each toward the other.

(3) Of or relating to each of two or more; held in common; shared.

(4) In corporate law, having or pertaining to a form of corporate organization in which there are no stockholders, and in which profits, losses, expenses etc, are shared by members in proportion to the business each transacts with the company:

(5) In informal use, an entity thus structured.

1470–1480: From the Middle English mutual (reciprocally given and received (originally of feelings)), from the Old & Middle French mutuel, from the Latin mūtu(us) (mutual, reciprocal (originally “borrowed”)), the construct being mūt(āre) (to change (source of the modern mutate (ie delta, omicron and all that))) + -uus (the adjectival suffix) + the Middle French -el (from the Latin –ālis (the third-declension two-termination suffix (neuter -āle) used to form adjectives of relationship from nouns or numerals) and rendered in English as –al.  Root was the primitive Indo-European mei- (to change, go, move).  The alternative spelling mutuall is obsolete.  Derived forms used to describe ownership structures such as quasi-mutual and trans-mutual are created as required.  Mutual & mutualist are nouns & adjectives, mutuality, mutualization, mutualism & mutualness are nouns, mutualize, mutualizing & mutualized are verbs and mutually & mutualistically are adverbs; the noun plural is mutuals.

The term "mutually exclusive" is widely used (sometimes loosely) but has a precise meaning in probability theory & formal logic where it describes multiple events or propositions such that the occurrence of any one dictates the non-occurrence of the other nominated events or propositions.  The noun mutualism is used in fields as diverse as corporate law, economic theory, materials engineering, political science and several disciplines within biology (where variously it interacts with and is distinguished from symbiosis).  The phrase "mutual admiration society" is from 1851 and appears to have been coined by Henry David Thoreau (1817–1862) to describe those who habitually were in agreement with each-other and inclined to swap praise.  The "mutual fund", although the structure pre-existed the adjectival use, is from 1950 and these soon came to be known simply as “mutuals”, the word appearing sometimes even in the registered names and the best known of the type were the building societies & benevolent (or friendly) societies, the core structural element of what was the ownership being held in common by the members rather than shareholders.  The concept of the mutual structure is of interest in some jurisdictions because of the suggestion the large assets held by chapters of the Freemasons may be so owned and, with the possibility the aging membership may ultimately result in these assets being dissolved and the proceeds distributed.  If, under local legislation, the structure was found to be mutual, membership might prove unexpectedly remunerative.

The Cold War's "mutually assured destruction" (MAD) is attested from 1963 (although it wasn’t until 1966 it entered general use) and was actually a modification of the Pentagon’s 1962 term “assured destruction” which was a technical expression from US military policy circles to refer to the number of deliverable nuclear warheads in the arsenal necessary to act as a deterrent to attack.  In the public consciousness it was understood but vaguely defined until 1965 when Robert McNamara (1916–2009; US Secretary of Defense 1961-1968) appeared before the House Armed Services Committee and explained the idea was "the minimum threat necessary to assure deterrence: the capability in a retaliatory nuclear attack to exterminate not less than one third the population of the Union of Soviet Socialist Republics (USSR)”.  The “mutual” was added as the number of deployable Soviet warheads reached a critical strategic mass.  The mastery of statistical analysis served McNamara well until the US escalation of the war in Vietnam when the Hanoi regime declined to conform to follow his carefully constructed models of behavior. 

In social media, a mutual is a pair of individuals who follow each other's social media accounts, whether by agreement or organically and there’s something a niche activity is working out the extent to which the behavior happens between bots.  Mutuality (reciprocity, interchange) was from the 1580s.  Mutually (reciprocally, in a manner of giving and receiving), was noted from the 1530s and the phrase mutually exclusive was first recorded in the 1650s.  The specialized mutualism (from the Modern French mutuellisme) dates from 1845, referring to the doctrine of French anarchist-socialist Pierre-Joseph Proudhon (1809-1865) that individual and collective well-being is attainable only by mutual dependence.  In the biological sciences, it was first used in 1876 to describe "a symbiosis in which two organisms living together mutually and permanently help and support one another" although there are those who differentiate mutualism (a type of co-existence where neither organism is directly affected by the other but the influence they exert on other organisms or the environment is of benefit to the other) from symbiosis (where there’s a co-dependency).

Parimutuel betting is from the French invention pari mutuel (mutual betting), the construct being pari (wager, from parier (to bet) from the Latin pariare (to settle a debt (literally “to make equal”)) from par, from paris (equal) + mutuel (mutual).  It describes a gambling system where all bets of a particular type are pooled and from this (gross-pool), taxes and the vigorish (from the Yiddish וויגריש‎ (vigrish), from the Russian вы́игрыш (výigryš) (winnings), the commission or “hose-take" are deducted.  The dividends are then calculated by dividing the remainder (net pool) by all winning bets.  In many jurisdictions it’s called the Tote after the totalisator, which calculates and displays bets already made; in Australia and New Zealand it’s the basis of the original agency structure of the Totalisator Agency Board (TAB).

The adoption of mutual as a synonym for "common" is from 1630s and was long condemned as being used “loosely, improperly and not infrequently, often by those who should know better”; “mutual friend" seemed the most common offence.  The view was that “mutual” could apply to only two objects and “common” should be used if three or more were involved.  Opinion has thankfully since softened.  Mutual and common (in the sense of the relation of two or more persons or things to each other) have been used synonymously since the sixteenth century and the use is considered entirely standard.  Objections are one of those attempts to enforce create rules in English which never existed, the only outcome being the choice of use treated as a class-identifier by those who care about such things and either ignored or un-noticed by most.  Tautologous use of mutual however should be avoided: One should say co-operation (not mutual co-operation) between two states.

Common (pronounced kom-uhn)

(1) Belonging equally to, or shared alike by, two or more or all in question (as in common property; common interests et al).

(2) Pertaining or belonging equally to an entire community, nation, or culture; public (as in common language; common history et al).

(3) Joint; united.

(4) Prevailing; Widespread; general; universal (eg common knowledge).

(5) Customary, habitual, everyday.

(6) In some jurisdictions a tract of land owned or used jointly by the residents of a community, usually a central square or park in a city or town (often as “the commons” or “the common”).

(7) In domestic & international law, the right or liberty, in common with other persons, to take profit from the land or waters of another, as by pasturing animals on another's land (common of pasturage ) or fishing in another's waters (common of piscary).  Of interest to economist and ecologists because of the disconnection between the economic gain from the commons and the responsibility for its care and management.

(8) Vulgar, ordinary, cheap, inferior etc (as a derogatory expression of class, often in phrases such as “common as muck” or “common as potatoes”, the back-handed compliment “the common-touch” applied to politicians best at disguising their contempt for the voters (or, as they refer to us: “the ordinary people”).

(9) In some (particularly Germanic) languages, of the gender originating from the coalescence of the masculine and feminine categories of nouns.

(10) In grammar, of or pertaining to common nouns as opposed to proper nouns.

(11) In the vernacular, referring to the name of a kind of plant or animal but its common (ie conversational) rather than scientific name (the idea reflected in the phrase “common or garden”).

(12) Profane; polluted (obsolete).

(13) Given to lewd habits; prostitute (obsolete).

(14) To communicate something; to converse, talk; to have sex; to participate; to board together; to eat at a table in common (all obsolete vernacular forms).

1250–1300: From the Middle English comun (belonging to all, owned or used jointly, general, of a public nature or character), from the Anglo-French commun, from the Old French, commun (Comun was rare in the Gallo-Romance languages, but reinforced as a Carolingian calque of the Proto-West Germanic gamainī (common) in the Old French and commun was the spelling adopted in the Modern French) (common, general, free, open, public), from the Latin commūnis (universal, in common, public, shared by all or many; general, not specific; familiar, not pretentious), thought originally to mean “sharing common duties,” akin to mūnia (duties of an office), mūnus (task, duty, gift), from the unattested base moin-, cognate with mean.  The Latin was from a reconstructed primitive Indo-European compound ḱom-moy-ni-s  (held in common), a compound adjective, the construct being ko- (together) + moi-n- (a suffixed form of the root mei- or mey (to change, go, move (hence literally "shared by all").  The second element of the compound was the source also of the Latin munia (duties, public duties, functions; specific office).  It was possibly reinforced in the Old French by the Germanic form of ḱom-moy-ni-s  (ko-moin-i) and influenced also the German gemein, and the Old English gemne (common, public).  Comun and its variations cam to displace the native Middle English imene & ȝemǣne (common, general, universal (from the Old English ġemǣne (common, universal)), and the later Middle English mene & mǣne (mean, common (also from the Old English ġemǣne)) and the Middle English samen & somen (in common, together (from the Old English samen (together)). A doublet of gmina.  Common is a noun, verb & adjective, commoner is a noun & adjective, commonality is a noun and commonly is an adverb; the noun plural is commons.

Common has been used disparagingly of women and criminals since at least the fourteenth century and snobs have added categories since as required.  The meanings "pertaining equally to or proceeding equally from two or more" & "not distinguished, belonging to the general mass" was from circa 1400 whereas the sense of "usual, not exceptional, of frequent occurrence" & "ordinary, not excellent" dates from the late fourteenth century.  Common prayer was that done in public in unity with other worshipers as contrasted with private prayer, both probably more common then than now.  The Church of England's Book of Common Prayer was first published in 1549 and went through several revisions for reasons both theological and political.  The 1662 edition remains the standard collection of the prayer books used in the Anglican Communion and while many churches now use versions written in more modern English, there remain traditionalists who insist on one of the early editions.

The common room was noted first in the 1660s, a place in the university college to which all members were granted common access.  The late fourteenth century common speech was used to describe both English and (less often) vernacular (which came to be called vulgar) Latin.  From the same time, the common good was an English adoption of the Latin bonum publicum (the common weal).  Common sense is from 1839 and is U whereas, because of the tortured grammar, 1848’s common-sensible is thought non-U.  The idea of common sense had been around since the fourteenth century but with a different meaning to the modern: The idea was of an internal mental power supposed to unite (reduce to a common perception) the impressions conveyed by the five physical senses (sensus communisin the Latin, koine aisthesis in the Ancient Greek). Thus it evolved into "ordinary understanding, without which one is foolish or insane" by the 1530s, formalised as "good sense" by 1726 with common-sense in the modern sense the nineteenth century expression.

The mid-fourteenth century common law was "the customary and unwritten laws of England as embodied in commentaries and old cases", as opposed to statute law.  Over the years, this did sometimes confuse people because in different contexts (common law vs statute law; common law versus equity; common law vs civil law) the connotations were different.  The phrase common-law marriage is attested from a perhaps surprisingly early 1909.  In the English legal system, common pleas was from the thirteenth century, from the Anglo-French communs plets (hearing civil actions by one subject against another as opposed to pleas of the crown).  In corporate law, common stock is attested from 1888.  The late fourteenth century commoner is from the earlier Anglo-French where in addition to conveying the expected sense of "one of the common people” also had the technical meaning “a member of the third estate of the estates-general".  In English it acquired the dual meaning as (1) of non-royal blood and (2), since the mid-fifteenth century “a member of the House of Commons”.  Commonly the adverb is from circa 1300 and commonness the noun from the 1520s though it originally meant only "state or quality of being shared by more than one", the idea of something of "quality of being of ordinary occurrence" not noted until the 1590s.  The adjective uncommon assumed a similar development, in the 1540s meaning "not possessed in common" and by the 1610s meaning "not commonly occurring, unusual; rare".

Last thoughts on a non-rule

The distinction between mutual (reciprocal; between two) and common (among three or more) probably once was, at least to some extent, observed by educated writers, Dr Johnson (1709-1984) in his A Dictionary of the English Language (1755) allowing but one definition: MUTUAL a. Reciprocal; each acting in return or correspondence to the other.

G K Chesterton.

That old curmudgeon G K Chesterton (1874-1936) was certainly convinced.  Writing about Charles Dickens (1812–1870) novel Our Mutual Friend (1864-1865), he claimed the title was the source of the phrase in general speech, snobbily noting of it was the “…old democratic and even uneducated Dickens who is writing here. The very title is illiterate. Any priggish pupil teacher could tell Dickens that there is no such phrase in English as 'our mutual friend'.  Anyone could tell Dickens that 'our mutual friend' means 'our reciprocal friend' and that 'our reciprocal friend' means nothing. If he had only had all the solemn advantages of academic learning (the absence of which in him was lamented by the Quarterly Review), he would have known better. He would have known that the correct phrase for a man known to two people is 'our common friend'."

The phrase in the English novel however pre-dated Dickens, Jane Austen (1775-1817) using it in both Emma (1816) and Persuasion (1818) and long before 1864, Mary Shelley (1797–1851), Sir Walter Scott (1771–1832), William Makepeace Thackeray (1811–1863), Herman Melville (1819–1891), James Fenimore Cooper (1789–1851) and Elizabeth Gaskell (1810–1865) all had “mutual friend” in their text.  Dickens, with the prominence afforded by the title and serialized in the press, doubtless popularized it and, as Chesterton well knew, literature anyway isn’t necessarily written in "common speech".  Whoever opened the floodgates, after 1864, mutual friends continued to flow, the writers George Orwell (1903-1950), Joseph Conrad (1857–1924), Jerome K Jerome (1859–1927), Rudyard Kipling (1865–1936), Mark Twain (1835-1910), Anthony Trollope (1815-1882), Henry James (1843–1916), Robert Louis Stevenson (1850–1894), Arthur Conan Doyle (1859–1930) and Church of England (broad faction) priest & historian Charles Kingsley (1819–1875) all content with "mutual friend" so those condemned by Chesterton are in good company.  The old snob probably did ponder if calling someone a “common friend” might create a misunderstanding but then, good with words, he’d probably avoid that by suggesting they were “rather common” or “a bit common" if that was what he wanted to convey, which not infrequently he often did.

Lindsay Lohan and her lawyer in court, Los Angeles, December 2011.

Clerestory

Clerestory (pronounced kleer-stawr-ee or kleer-stohr-ee)

(1) In architecture, a portion of an interior rising above adjacent rooftops, fitted with windows admitting daylight.

(2) In church architecture, a row of windows in the upper part of the wall, dividing the nave from the aisle and set above the aisle roof (associated particularly with the nave, transept and choir of a church or cathedral.

(3) In transportation vehicles (usually busses, railroad cars and occasionally cars & vans), a raised construction, typically appended to the roof structure and fitted with (1) windows to admit light or enhance vision or (2) slits for ventilation (or a combination of the two).

1375–1425: From the late Middle English, the construct being clere (clear (in the sense of “light” or “lighted”)) + story (from storey (a level of a building).  The word is obviously analyzed as “a story (upper level) with light from windows”.  Storey was from Middle English stori & storie, from the Anglo-Latin historia (picture), from the Latin, from the Ancient Greek ἱστορία (historía) (learning through research, narration of what is learned), from ἱστορέω (historéō) (to learn through research, to inquire), from ἵστωρ (hístōr) (the one who knows, the expert, the judge).  In the Anglo-Latin, historia was a term from architecture (in this case “interior decorating” in the modern sense) describing a picture decorating a building or that part of a building so decorated.  The less common alternative spellings are clearstory & clerstory.  Clerestory is a noun and clerestoried is an adjective; the noun plural is clerestories.

From here was picked up the transferred sense of “floor; level”.  The later use in church architecture of “an upper story of a church, perforated by windows” is thought simply to be a reference to the light coming through the windows and there is nothing to support the speculation the origin was related to a narrative (story) told by a series of stained glass windows, illuminated by sunlight.  Historians have concluded the purpose of the design was entirely functional; a way of maximizing the light in the interior space.  The related architectural design is the triforium.  The noun triforium (triforia or triforiums in the plural) (from the Medieval Latin triforium, the construct being tria (three) + for (opening) + -ium) describes the gallery of arches above the side-aisle vaulting in a church’s nave.  The –ium suffix (used most often to form adjectives) was applied as (1) a nominal suffix (2) a substantivisation of its neuter forms and (3) as an adjectival suffix.  It was associated with the formation of abstract nouns, sometimes denoting offices and groups, a linguistic practice which has long fallen from fashion.  In the New Latin, it was the standard suffix appended when forming names for chemical elements.

Clerestories which once shone: Grand Central Terminal (the official abbreviation is GCT although the popular form is "Grand Central Station" (often clipped to "Grand Central")), Midtown Manhattan, New York City, 1929 (left) and the same (now dimmed) location in a scene from the Lindsay Lohan film Just my Luck (2006) (right).  Because of more recent development in the surrounding space, the sunlight no longer enters the void through the clerestoried windows is such an eye-catching way.  In modern skyscrapers, light-shafts or atriums can extend hundreds of feet.

Tourist boat on a canal cruise, Amsterdam, the Netherlands.

Boats with clerestory windows are commonly seen on waterways like the canals of Amsterdam and are valued by tour-guides because they make excursions possible in (almost) all-weathers.  Those designing passenger busses and train carriages were also early adopters of clerestory windows, initially because they were a source of “free” light but as packaged tourism developed into “sightseeing”, tour operators recognized the potential and commissioned versions optimized for outward visibility, essentially a form of “value-adding” which made even the dreary business of bus travel from one place to the next more of a “sightseeing” experience, something probably most valued by those afforded a greater vista to observe in mountainous regions.

Greyhound Scenicruiser in original livery.

A variation of the idea was used for long-distance busses in North America, the best known of which remains the Greyhound Scenicruiser (PD-4501), featuring a raised upper deck with a clerestory windscreen.  Although the view through that was enjoyed by many passengers, the design was less about giving folk a view and more a way to maximize revenue within the length restrictions imposed by many US states.  What the upper deck did was allow a increase in passenger numbers because the space their luggage would absorb in a conventional (single layer) design could be re-allocated to people, their suitcases (and in some cases also freight, another revenue stream) relegated to the chassis level which also improved weight distribution and thus stability.

A predecessor: 1930 Lancia Omicron.

Famous as it became, the Scenicruiser, 1001 of which were built by General Motors (GM) between 1954-1956, was to cause many problems for both manufacturer and operator, the first of which caused by the decision to use twin-diesel engines to provide the necessary power for the new, heavy platform.  The big gas (petrol) units available certainly would have provided that but their fuel consumption would not only have made their operation ruinously expensive (both the fuel burn and the time lost by needing frequently to re-fill) and the volume of gas which would have to be carried would have both added to weight and reduced freight capacity.  Bigger GM diesel units weren’t produced in the early 1950s so the twin engines were a rational choice and the advantages were real, tests confirming that even when fully loaded, the coupled power-train would be sufficient for hill climbing while on the plains, the Scenicruiser happily would cruise using just a single engine.  However, as many discovered (on land, sea and in the air), running two engines coupled together is fraught with difficulties and these never went away, the busses eventually adopting one of GM’s new generation of big-displacement diesels as part of the major re-building of the fleet in 1961, a programme which also (mostly) rectified some structural issues which had been recognized.  Despite all that, by 1975 when Greyhound retired the model, the company still had hundreds in daily service and many of those auctioned off were subsequently used by other operators and in private hands, some are still running, often as motor homes or (mostly) static commercial displays or museum exhibits.

1951 Pegaso Z-403 (left) and 1949 Brill Continental (right).

GM’s Scenicruiser was influential and clerestory windscreens soon proliferated on North American roads although the idea wasn’t new.  The Spanish manufacturer Pegaso (a creation of Generalissimo Francisco Franco’s (1892-1975; Caudillo of Spain 1939-1975) industrial policy) between 1951-1957 produced the Z-403 (1951-1957) which used the same design and before even that a bus with an almost identical profile had been sold in the US by the JG Brill Company, albeit with a conspicuous lack of success.  As early as 1930 the Italian concern Lancia offered the Omicron bus with a 2½ half deck arrangement with a clerestoried upper windscreen.  The Omicron’s third deck was configured usually as a first-class compartment but at least three which operated in Italy were advertised as “smoking rooms”, the implication presumably that the rest of the passenger compartment was smoke-free.  History doesn't record if the bus operators were any more successful in enforcing smoking bans than the usual Italian experience.

1968 Oldsmobile Vista Cruiser.

One quirky offering which picked up the Scenicruiser’s clerestoried windscreen was the Oldsmobile Vista Cruiser (1964-1977), a station wagon which, until the release of the third series in 1973 featured one at the leading edge of a raised roof section, the glass ending midway over the backseat, the shape meaning it functioned also as a “skylight”.  Above the rear side windows were matching clerestories which might sound a strange thing to add above a luggage compartment but during those years, a “third seat” was a popular option to install in the space, transforming the things into eight or nine seat vehicles; families were bigger then.  The Vista Cruiser sold well and Buick later adopted the idea for some of its range until the concept was abandoned in 1972 because of concerns about upcoming safety regulations.  Such rules were however never imposed and both manufacturers revived the idea in the 1990s for their (frankly ugly) station wagons and when the Buick was discontinued in 1996, it was the last full-sized station wagon to be made in the US, the once popular market segment cannibalized to the point of un-viability by the mini-van (people-mover) and the sports utility vehicle (SUV).

The arrangement of a series of windows in a high-mounted row, borrowed from architecture, became familiar on train carriages and buses, especially those which plied scenic routes.  Usually these were added to the coachwork of buses built on existing full-sized commercial chassis which could seat 40-60 passengers but in the 1950s, there emerged the niche of the smaller group tour, either curated to suit a narrower market or created ad-hoc by hotels or operators; smaller vehicles were required and these offered the additional advantage of being able sometimes to go where big buses could not.  In places like the Alps, where those on the trip liked to look up as well as out, rows of clerestoried windows were desirable.

1959 Volkswagen Microbus Deluxe (23 Window Samba). 

The best known of these vehicles was the Volkswagen “Samba”, a variation of the Microbus, one of the range of more than a dozen a models built on the platform of the Type 2, introduced in 1950 after a chance sighting by a European distributer of a VW Beetle (Type 1) chassis which had been converted by the factory into a general-purpose utility vehicle.  The company accepted the suggestion a market for such a thing existed and in its original, air-cooled, rear-engined configuration, it remained in production well into the twenty-first century.  Between 1951-1966, the Microbus was available in a “Deluxe” version which featured both a folding fabric sunroof and rows of rows of clerestoried windows which followed the curve of the sides of the roof.  Available in 21 & 23 window versions, these are now highly collectable and such is the attraction there’s something of a cottage industry in converting Microbuses to the clerestoried specification but it’s difficult exactly to emulate the originals, the best of which can command several times the price of a fake (a perfectly restored genuine Samba in 2017 selling at auction in the US for US$302,000).  Such was the susceptibility to rust, the survival rate wasn’t high and many led a hard life when new, popular with the tour guides who would conduct bus-loads of visitors on (slow) tours of the Alps, the sunroof & clerestory windows ideal for gazing at the peaks.  To add to the mood, a dashboard-mounted valve radio was available as an option, something still for many a novelty in the early 1950s.  The Microbus Deluxe is rarely referred to as such, being almost universally called the “Samba” and the origin of that in uncertain.  One theory is it’s a borrowing from the Brazilian dance and musical genre that is associated with things lively, colorful, and celebratory, the link being that as well as the sunroof and windows, the Deluxe had more luxurious interior appointments, came usually in bright two-tone paint (other Type 2s were usually more drably finished) and featured lashings of external chrome.  It’s an attractive story but some prefer something more Germanic: Samba as the acronym for the business-like phrase Sonnendach-Ausführung mit besonderem Armaturenbrett (sunroof version with special dashboard).  However it happened, Samba was in colloquial use by at least 1952 and became semi official in 1954 when the distributers in the Netherlands added the word to their brochures.  Production ended in July 1967 after almost 100,000 had been built.

1966 Volkswagen Samba (21 Window, Left) and 1962 Volkswagen Samba (23 Window, Right).  The 23 Window van is a conversion of a Microbus and experts (of which there seem to be many, such is the following these things have gained) say it's close to impossible exactly to replicate a factory original.  In theory, the approach would be to take the parts with serial numbers (tags, engine, gearbox etc) from a real Samba which has rusted into oblivion (something not uncommon) and interpolate these into the sound body of a Microbus with as close a build date as possible.  Even then, such are the detail differences that an exact replication would be a challenge.  Because the Sambas received the same running changes and updates as the rest of the Microbus range, there was much variation in the details of the specification over the years but the primary distinction is between the “21” & “23” window vans, the difference accounted for by the latter’s pair of side-corner windows to the left & right of the rear top gate opening.  In 1964, when the rear doors were widened, the curved windows in the roof were eliminated because there would no longer be sufficient metal in the coachwork to guarantee structural integrity.