Perpendicular. Third and latest of the English Gothic architectural styles, also known as Third Pointed or Rectilinear, it followed from the previous Decorated or Second Pointed style. The Perp. style first emerged in designs of c.1332 for the chapter-house and cloisters of old St Paul's Cathedral, London (destroyed), by William de Ramsey: key Perp. details, including mullions extending to the soffits of window-arches; extensive use of the bowtell; developed employment of the double-ogee; quatrefoils set in squares; bases with circular rolls, bells, and cushions over octagonal sub-bases of bell form; four-centred arches with flattened upper arcs; and square-framed arches with cusped blind spandrels were all evident. So the Perp. style emerged in the first half of C14 in London, and was further developed at Gloucester Cathedral, where the chancel (c.1337–57) displays many of its attributes, including the panel-like effect created by vertical and horizontal elements. An English style, it has no Continental, Irish, or Scottish equivalent, and survived for more than three centuries (the fan-vaulted hall staircase at Christ Church, Oxford, is c.1640). It was the first of the Gothic styles to be revived in C18.

Perp. is immediately recognizable by its pronounced verticals and horizontals in blind panels covering wall surfaces and in tracery (where the transoms are often ornamented with miniature battlements, and mullions rise straight up to the soffits of window-openings). Apertures gradually acquired flatter tops, with arches of the four-centred type. Vaults evolved from the complicated varieties involving liernes into the fan-vaults first found at the Chapter House of Hereford Cathedral (destroyed 1769) and the Cloisters of Gloucester Cathedral (both second half of C14), and developing into the spectacular fan-vaulting of King's College Chapel, Cambridge (early C16), and the Lady Chapel (or Chapel of King Henry VII (reigned 1485–1509)) at Westminster Abbey (1503–19). Rectangular mouldings framing door-or window-openings formed spandrels (often ornamented) reinforcing the controlled panel-like appearance: those hood-mouldings terminated in carved label-stops. Indeed, the panel motif is one of the most recognizable features of the style, each framed panel having an arched top, often cusped, and is repeated in rows in tracery and over the walls as blind panels. Windows got larger, composed of many lights (repeating the panel-like forms), and often filled the entire wall between buttresses.

The Perp. style is commonly found in parish-churches, especially in East Anglia, the Cotswolds, and Somerset, where great wealth was created by the wool trade. Clerestoreys were added to existing churches, and they often were vast, airy, and light: as naves were increased in height to accommodate ranges of large Perp. windows in their clerestoreys, roofs were flattened, and disappeared behind crenellated decorative parapets. In East Anglia, especially, chancels were not distinctly compartmented, being part of the main volume of the church, but demarcated by means of elaborate timber screens, often sumptuously decorated and coloured. Mouldings tended to become mechanical, and foliage less deeply cut than previously: a common moulding was the grapevine or trail, often found on screens and canopies.

The use of hood-mouldings, the flattening of roofs and arches, the adoption of wide-spread crenellations, and the elaboration of lierne- and later fan-vaulting gave the Perp. style its predominant flavour. Perp. architecture from the end of C15 to the beginnings of the Elizabethan style is often called Tudor, and frequently featured brick walls ornamented with diaper-work, very flattened arches, and prominent hood-mouldings. The Tudor style was revived in C19, often for schools, work-houses, and collegiate buildings.

Bibliography

Harvey (1978);
W. Papworth (1852)
J. Parker (1850)

Perpendicular

Phalangers are a small group of arboreal mammals belonging to the family Phalangeridae, of which 26 species are recognized in six genera. Phalangers, more commonly known as possums and cuscuses, are marsupials but with a vague resemblance to some monkeys. Indeed many early European explorers thought that they were monkeys. These species occur in Australia, New Guinea and adjacent islands west to Sulawesi (Indonesia) and east to the Solomon Islands. New Guinea is thought to be the main center for evolution of these species with eight species represented. In addition to their natural range, some species have been introduced, such as the brushtail possum (Trichosurus vulpecula ) to New Zealand (for their valuable fur) and the common cuscus (Phalanger orientalis ) to the Solomon Islands.

Phalangers are short, compact animals with thickly furred bodies. A wide range of colors occur from the predominantly reddish brown fur of the common cuscus to the pure white coat with dark spots of the spotted cuscus (Spilocuscus maculatus ) and the strikingly marked black-spotted cuscus (S. rufoniger ), the largest of all phalangers with a black back, orange-russet limbs, white underside and russet and white head. In most species the short ears are concealed by the thick fur. Their limbs are adapted to climbing, with sharp, curved claws for climbing and clawless, but opposable, first hind toes that assist with grasping small branches. They also have a strong prehensile tail, which is usually bare towards the tip. Phalangers aremost active at night— their large, forward-pointing eyes enable them to receive sufficient light to guide them through the tangle of branches and leaves in the forest canopy. A wide range of food items are taken, including young leaves, buds, shoots, fruit, and occasionally insects, birds eggs, and small lizards.

Little is known about the social behavior of many of these species. Phalangers are probably capable of breeding throughout the year, but apart from when females are receptive to breeding, they all appear to be solitary animals, occupying a range of 7.5–20 acres (3–8 ha), depending on food, shelter and population density. In the wild, phalangers are relatively long-lived animals, with some living up to 13 years of age.

Possums and cuscuses are well-known to humans—possums, in particular, for the economic damage they cause in timber plantations, as well as for their crop-raiding habits. In New Zealand, the damage caused to native vegetation has also been significant, as most of these trees evolved in the absence of foliage-feeding animals and are therefore unable to produce enough toxins to repel attack. It is also thought that the common brushtail may spread tuberculosis, which has led to a major eradication scheme of this species in New Zealand.

As they rarely come down to the ground, possums and cuscuses have few natural predators, apart from large birds of prey and snakes. Human activities are thought to have had a major impact, at least on certain species, through habitat destruction which, in certain cases, is made worse by hunting pressure. Although the precise conservation status of most species is still uncertain, at least two species—the Telefomin cuscus (Phalanger matanim ) of Papua New Guinea and the black-spotted cuscus of Papua New Guinea and Indonesia—are considered endangered by the IUCN. These two species appear to be threatened by deforestation, habitat degradation, and, possibly, overhunting. Another species about which very little is known is the scaly-tailed possum (Wyulda squamicaudata )—the only species in its genus—known from northwestern Australia. In New Guinea, most species of cuscus are hunted for their meat and prized fur which is worn at special ceremonies. It is essential that appropriate conservation measures are taken to protect the native habitat of all of these species and to fully evaluate the extent of threats facing them from habitat loss and hunting.

per·pen·dic·u·lar / ˌpərpənˈdikyələr/ • adj. 1. at an angle of 90° to a given line, plane, or surface: dormers and gables that extend perpendicular to the main roofline. ∎  at an angle of 90° to the ground; vertical: the perpendicular cliff. ∎  (of something with a slope) so steep as to be almost vertical: guest houses seem to cling by faith to the perpendicular hillside.2. (Perpendicular) denoting the latest stage of English Gothic church architecture, prevalent from the late 14th to mid 16th centuries and characterized by broad arches, elaborate fan vaulting, and large windows with vertical tracery: the handsome Perpendicular church of St. Andrew.• n. a straight line at an angle of 90° to a given line, plane, or surface: at each division, draw a perpendicular representing the surface line. ∎  (usu. the perpendicular) perpendicular position or direction: the wall declines from the perpendicular a little inward. ∎  an instrument for indicating the vertical line from any point, as a spirit level or plumb line.DERIVATIVES: per·pen·dic·u·lar·i·ty / -ˌdikyəˈlaritē/ n.per·pen·dic·u·lar·ly adv.

Perpendicular

The term perpendicular, in geometry, describes a pair of lines or planes that intersect each other at a 90-degree angle. Perpendicularity is an important concept in mathematics, science, engineering, and other fields. A line L1 is perpendicular to a line L2 if the two intersect with congruent adjacent angles, which means that the angles are both equal to 90 degrees. Of course, a purely analytical definition of the term exists, also. If one defines the slope m of a line as rise over run, then m = (y2 – y1)/(x2 – x1). A pair of non-vertical lines L1 and L2 are perpendicular if and only if m1m2 = -1.

The concept of perpendicularity applies to any combination of lines and planes. Two or more planes can be perpendicular, or a line can be perpendicular to a plane, or to any number of parallel planes. Sometimes the term orthogonal is used with the same meaning, although orthogonal is also used outside of geometry and perpendicular is not. In science and engineering, a line perpendicular to another line or a plane is often referred to as being normal to the plane, or simply called the surface normal.

The concept of perpendicularity is a fundamental building block of geometry. It allows mathematicians and scientists to define figures such as squares and parallelpipeds, for example, and to draw conclusions about the relationships of the angles in certain types of figures such as triangles. The common x-y or xyz coordinate system on which geometrical figures and scientific data are plotted is defined by a set of perpendicular, or orthogonal, lines. The right triangles from which mathematicians define most of the basic relationships of trigonometry are based on a pair of perpendicular lines. Analytical geometry and vector calculus, which are an indispensable tool in engineering and science, make continual use of the concept.

Constructing a line perpendicular to another line is simple. Using a compass, measure equal distances both to the left (L_L) and to the right (L_R) of point P by putting the point of the compass on P and marking L_L and L _R. Then place the compass point on L_L and scribe a short arc, then place the compass point on L_R and find the arc that intercepts the first arc. The line that connects point P to intercept X is perpendicular to the original line L.

Kristin Lewotsky

Perpendicular

The term perpendicular describes a pair of lines or planes that intersect each other at a 90 degree angle . Perpendicularity is an important concept in mathematics , science, and engineering . A line l1 is perpendicular to a line l2 if the two intersect with congruent adjacent angles, which means that the angles are both equal to 90 degrees. Of course, a purely analytical definition of the term exists, also. If we define the slope m of a line as rise over run, then m = (y2 - y1)/(x2 - x1). A pair of nonvertical lines l1 and l2 are perpendicular if and only if m1m2 = -1.

The concept of perpendicularity applies to any combination of lines and planes. Two or more planes can be perpendicular, or a line can be perpendicular to a plane , or to any number of parallel planes. Sometimes the term orthogonal is used with the same meaning, although orthogonal is also used outside of geometry and perpendicular is not. In science and engineering, a line perpendicular to another line or a plane is often referred to as being normal to the plane, or simply called the surface normal.

The concept of perpendicularity is a fundamental building block of geometry. It allows us to define figures such as squares and parallelpipeds, for example, and to draw conclusions about the relationships of the angles in certain types of figures such as triangles. The common xy or xyz coordinate system on which we plot geometrical figures and scientific data alike is defined by a set of perpendicular, or orthogonal, lines. The right triangles from which we define most of the basic relationships of trigonometry are based on a pair of perpendicular lines. Analytical geometry and vector calculus , which are an indispensible tool in engineering and science, make continual use of the concept.

Constructing a line perpendicular to another line is simple. Using a compass, measure equal distances both to the left (Ll) and to the right (Lr) of point P by putting the point of the compass on P and marking Ll and L r. Then place the compass point on Ll and scribe a short arc , then place the compass point on Lr and find the arc that intercepts the first arc. The line that connects point P to intercept X is perpendicular to the original line L.

Kristin Lewotsky