What are flying buttresses? describe how and why they are used.

The flying buttress (arc-boutant, arch buttress) is a specific form of buttress composed of an arch that extends from the upper portion of a wall to a pier of great mass, in order to convey to the ground the lateral forces that push a wall outwards, which are forces that arise from vaulted ceilings of stone and from wind-loading on roofs.

The defining, functional characteristic of a flying buttress is that it is not in contact with the wall at ground level, unlike a traditional buttress, and so transmits the lateral forces across the span of intervening space between the wall and the pier. To provide lateral support, flying-buttress systems are composed of two parts: (i) a massive pier, a vertical block of masonry situated away from the building wall, and (ii) an arch that bridges the span between the pier and the wall — either a segmental arch or a quadrant arch — the flyer of the flying buttress

Explanation:

As a lateral-support system, the flying buttress was developed during late antiquity and later flourished during the Gothic period (12th–16th c.) of architecture. Ancient examples of the flying buttress can be found on the Basilica of San Vitale in Ravenna and on the Rotunda of Galerius in Thessaloniki. The architectural-element precursors of the medieval flying buttress derive from Byzantine architecture and Romanesque architecture, in the design of churches, such as Durham Cathedral, where arches transmit the lateral thrust of the stone vault over the aisles; the arches were hidden under the gallery roof, and transmitted the lateral forces to the massive, outer walls. By the decade of 1160, architects in the Île-de-France region employed similar lateral-support systems that featured longer arches of finer design, which run from the outer surface of the clerestory wall, over the roof of the side aisles (hence are visible from the outside) to meet a heavy, vertical buttress rising above the top of the outer wall.

Flying buttress of Reims Cathedral, as drawn by Villard de Honnecourt

The advantage of such lateral-support systems is that the outer walls do not have to be massive and heavy in order to resist the lateral-force thrusts of the vault. Instead, the wall surface could be reduced (allowing for larger windows, glazed with stained glass), because the vertical mass is concentrated onto external buttresses. The design of early flying buttresses tended to be heavier than required for the static loads to be borne, e.g. at Chartres Cathedral (ca. 1210), and around the apse of the Saint Remi Basilica, which is an extant, early example in its original form (ca. 1170). Later architects progressively refined the design of the flying buttress, and narrowed the flyers, some of which were constructed with one thickness of voussoir (wedge brick) with a capping stone atop, e.g. at Amiens Cathedral, Le Mans Cathedral, and Beauvais Cathedral.

The architectural design of Late Gothic buildings featured flying buttresses, some of which featured flyers decorated with crockets (hooked decorations) and sculpted figures set in aedicules (niches) recessed into the buttresses. In the event, the architecture of the Renaissance eschewed the lateral support of the flying buttress in favour of thick-wall construction. Despite its disuse for function and style in construction and architecture, in the early 20th century, the flying-buttress design was revived by Canadian engineer William P. Anderson to build lighthouses

a caption indicating the purpose of the diagram

explanation:

yes as the core issue is an ever increasing majority of human workers   will become permanently unemployed as ever cheaper ever more intelligent automated machines inevitably replace more expensive human workers with each passing year.

economic growth now and in the future requires that fewer jobs are created for human workers. this is the desirable inevitable consequence. the automation of the jobs of human workers is the most profitable economically productive activity on the planet.

so as a global society we need to have a plan to deal with this inevitable change.

automation has been, is and will always be a friend to human society if human society on a global basis is prepared to deal with the inevitable consequences.

what is key is that automation killing all jobs is only a matter of when not if.

the real question is can we get past the now invalid assumption that most humans can work for a decent wage going forward.

i spent my working career increasing automation and increasing efficiency. this consequently reduces the hours worked by humans while increasing the output economic goods and services at an ever decreasing price.

why not have ever cheaper ever more intelligent automated machines create the vast majority of required economic goods and services as opposed to human workers?

why not have most human workers working less and retiring earlier?

there is much more to life than working forever.

fortunately, automation has been going on for decades and will continue as an irreversible process as ever cheaper ever more intelligent automated machines permanently replace more costly human workers.

i write this answer for the people that have an open mind and are not living in the past this is what i feel most effectively deals with the tractable issues that automation creates.

the question at hand is how we deal with automation going forward as a society.

automation is only a threat because society has yet to acknowledge automation is happening let alone effectively a having a plan to address it.

a conservative libertarian free market idea where individuals choose what economic goods and services are produced in the free market as the free market supply will respond to free market demand. this is not a centrally planned communist economy.

it is yes as the core issue is an ever increasing majority of human workers   will become permanently unemployed as ever cheaper ever more intelligent automated machines inevitably replace more expensive human workers with each passing year.

economic growth now and in the future requires that fewer jobs are created for human workers. this is the desirable inevitable consequence. the automation of the jobs of human workers is the most profitable economically productive activity on the planet.

so as a global society we need to have a plan to deal with this inevitable change.

automation has been, is and will always be a friend to human society if human society on a global basis is prepared to deal with the inevitable consequences.

what is key is that automation killing all jobs is only a matter of when not if.

the real question is can we get past the now invalid assumption that most humans can work for a decent wage going forward.

i spent my working career increasing automation and increasing efficiency. this consequently reduces the hours worked by humans while increasing the output economic goods and services at an ever decreasing price.

why not have ever cheaper ever more intelligent automated machines create the vast majority of required economic goods and services as opposed to human workers?

why not have most human workers working less and retiring earlier?

there is much more to life than working forever.

fortunately, automation has been going on for decades and will continue as an irreversible process as ever cheaper ever more intelligent automated machines permanently replace more costly human workers.

i write this answer for the people that have an open mind and are not living in the past this is what i feel most effectively deals with the tractable issues that automation creates.

the question at hand is how we deal with automation going forward as a society.

automation is only a threat because society has yet to acknowledge automation is happening let alone effectively a having a plan to address it.

a conservative libertarian free market idea where individuals choose what economic goods and services are produced in the free market as the free market supply will respond to free market demand. this is not a centrally planned communist economy.

hope this