Post 608 by Gautam Shah



Doors, Gates, Windows, and Gaps express the concept of transition from one state of existence to another. Likewise Passageways, Bridges, Ducts, also serve the chief function of transition, and other functions of openings by means of barricading, demarcating and framing. Some words, such as in and out, from and to, through, etc., denote entry-exit from a space. Similarly components like portals, jambs, lintels, arches, door-heads, thresholds, eves, gateways, sill, etc. singly or with their natural affinitive relationships also represent the opening system.



Masai house door Flickr image by Kenya John Atherton

The openings have a natural simultaneity of two faces, and so are dilemmatic in affectations. Janus, the Roman God of doors was a two-faced person. In literature the duality has been used to elaborate or prolong the process of conclusive action. The openings are natural or enforced edges. The openings manifest over the edges recognizing the domains of distinctions on either side. The division, is made recognizable through superlative structures like fort-walls, abutments, portals, dykes, bunds, piers, moats, barricades, etc.



In literature, on crossing an edge, change manifests. The change is seen through the scenic depiction, and also by psychical referencing. The literary-constructs present 3-way experience, of being on one or the other face, and the state of being into neither of these. The paired reality of inside and outside, or existing on one side versus the other side, creates a threshold or a Rekha (a line). The line is so thin that one has to be on one or the other side of it. But architectural entities have three-dimensional constructs, and so provide an intervening space or an Antarvedi*.

Hemchandracharya, (a Jain saint and scholar of Patan, Gujarat, India, 1088-1173) referred to such a situation as Antarvedi* (a space between two realms or a verandah). Such a condition occurs in case of Doab (a land between two water bodies -such as Punjab-India). Antarvedi is also a village situated at the Bay of Bengal and Vashista Godavari, a tributary of the Godavari River in Andhra, India.


Antarvedi -a verandah at Kalleshwara Temple Hadagali, Bellary district Karnataka India > Wikipedia image by Dineshkannambadi

 ‘Often crossing a threshold, real or implied, shifts us between safety of the known and anxiety of the unknown. Thus, working on literal and symbolic levels simultaneously, the doors and other openings offer, both, the physical reality of protection, and represent the psychological idea of safety. To stand upon the threshold permits contemplation before committing to circumstances, which once taken, may not be undone. On crossing a threshold, there is no going back to what was.’


Pax ingrangibus salus exeuntibus (peace to those who arrive, safety to those who leave) Tyntesfield Wraxall N Somerset England Flickr image by Peter Reed

A Latin phrase, ‘Pax intrantibus, salus exeuntibus’ (or ‘Intrantibus pax, exeuntibus salus’) is an ancient inscription, seen at the entrances of Benedictine monasteries, schools, inns, on gates, and at the front door or vestibule of private homes. This is translated in English: ‘Peace to those who enter, good health (or safety) to those who depart’. It states that whatever is within, is familiar and so likely of security, in comparison to what exists beyond the unknown and dangerous. This is at a complete variance from Tolkien’s (author of Lords of the rings, etc.) as he inverts the usual association of ‘being inside’ with safety, and ‘being outside’ with danger. The insides are friends and relatives who could be treacherous, but on outsides one must be on guard of the enemies. It is only by venturing outside and crossing the edge that we come to know our true selves.


In the Hobbit, The Lord of the Rings and other writings, the expansive Greenwood the Great was called Mirkwood > Wikipedia image by Dominik Matus

J R R Tolkien frequently refers to a door, window, gate, or other passageways to convey a change in a character’s physical, metaphysical or metaphorical state. Tolkien’s dark woodland imagery is tunnel-like juxtaposed with the open land forest. Entering a forest (as is entering into water, caves, and barrows) is like going into a dark unknown, and coming out, is gaining knowledge and confidence. Tolkien gave as much attention to literary descriptions as much to visual treatments (sketches and paintings) of the doorways, gates, windows and thresholds. In his landscape sketches, the focal point is almost always a doorway or other opening.

DOOR and the IDEA of BECOMING : One of the metaphorical meanings of doorways and openings in Tolkien’s work conveys the idea of ‘becoming’. As one passes through the doorway and enters a new stage of development or experience, having gained the ‘key’ necessary to move forward, one ‘becomes’ something more—more capable, more perceptive, more knowledgeable. Although, we often cling to our comfort zone, it is only by venturing outside our experience that we come to know our true selves. In other words, we must cross the thresholds that paradoxically lead us both outward and inward to a deeper understanding of our strengths and weaknesses and recognition of our relationships with the cosmos, just like Tolkien’s fish out of water.


An opening is perceived to be parallel to the gravity entity so in-out or exit-entry occur on a horizontal plane, but never up-down or over-under. Going down (or up) a stair or hill, do not signify the ‘door or the gate’. Even for the gate to heaven or hell the door is always parallel to the gravity. Going down is compared to entering or leaving a womb. The transition is never up (to heaven) or down (to hell). Going down happens for the burial tomb or dungeon for imprisonment. But openings may not take one outside or inside, such as the Japanese Torri Gates.


Japanese Torri gate at Itsukushima shrine > Wikipedia image by Rdsmith4


Going down ‘in to a womb’ > Wikipedia image by Alex Proimos from Sydney Australia


SPACE PERCEPTION – Issues for Design -4

Post 607 by Gautam Shah 



Faculties of Perceptions > Wikipedia image by Abellman

Perception is becoming aware of Objects and Environment. A person has natural or nominal capacities for sensorial perception. The sensorial faculties, though vary from person to person, and also depend on many other factors such as age, sex, moods, past experiences, sequences of happenings, motivation, learning capacity. The capacities are improved by various means of reach such as spectacles, hearing aids, insulators. The perception is also regulated by conversion processes, which diffuse, hasten, or delay through condensation, compression, enlargements, focussing, differentiation, etc. Perception of Objects in a space occurs as a sequence of events, where each segment is affected by the varying environment and the position of the perceiver.


Algerian Nomads habitat > Wikipedia + Flickr image by Tonton Jaja

The word Perception derives from Latin perceptiō (a receiving or collecting, taking cognizance of, intuitive or direct recognition of some innate quality, obtain, gather, seize entirely, take possession of, to grasp with the mind, learn, comprehend).


Shutting off the vision > Wikipedia image by davric

Perception occurs as congregation of several effects, and mutually compensative processes. We may not be able to isolate few parts of it. As for example, Smell and Taste often occur together. The sensory nodes have FIVE important characteristics that they have specific Location, Capacity and Multiplicity and the Duration.

● The Locations of the sensorial nodes provide information about the directionality, and encourages discrimination.

● The Capacity of the perceptive nodes is range bound which permit selections while providing comfort, sense of survival. Beyond the range bound capacity of the perception faculty, the perception process gets transmitted to other modes allowing different facilitation.

● The Multiplicity of nodes gives a sense of scale and referential positions.

● The Duration of perception gives a temporal scale. In other words The Location, Body capacities, Multiplicity and duration, all together and individually endow a Geo-Spatial identity.

● There are abnormal sensorial perceptions also. These arise from the Location related misinterpretations, Physiological deficiencies, differentiated perception of multiple nodes and time related intensifications and diffusions.


Realization – Cognition > Wikipedia image

The process of cognition reveals how the environment is formatted, organized and represented in time and space. Environment helps in identification, and interpretation of the space, and so gives a measure to it. The measures are perceived because we have different types nodes of perception, where some have multiple and directional locations. The nodes also have a range bound capacity, beyond and under which the reception gets transferred to other systems, or ceases to be operative. With these operants’ one gets a sense of scale, size, gradations like concentration and diffusion, framing, juxtaposing, referencing, linkages, details and orientation.


The Singing Tree (Burnley Panopticon) > a wind powered sound installation at Lancashire England > Wikipedia image by Childzy

Perception nominally means sensorial cognition, but could also be realization through other means. An understanding of a situation, acceptance or confirmation, are also part of the process of perception. There are some realizations that may not be attributed to sensorial nodes. Such non sensorial cognition makes us aware of orientations such as North, East, West, South, Up, Down, Front, Back, movements, acceleration-deceleration, energy flows, gravity, etc. There are other realizations that do not relate to physical perceptions, but are sometimes attributed to psychical experiences. These include empathy, sympathy, links or relationships between two objects and organisms, acknowledgement, familiarity, recollection of past events, fore-sightings, future purposes or utilities of objects and situations, orders in complex situations, hierarchies in multiple entities, etc. Cognition also involves forming expectations, directing the attention, learning and memory retention. At some level cognition is recognizing a thought, intuition, deduction, etc.


Immersion into Virtual reality is a perception of being physically present in a nonphysical world > Wikipedia image

Objects are positioned in the Space, where the Environment manifests as a happening, marking the Time. In this sense a space and time form a matrix of relationship, and perception is becoming aware of such a matrix. Space perception is about recognizing the extent, gaining knowledge and schematising for means for sustaining the occupation. Perception is also regarded as ‘the modification of anticipation’ because some disequilibrium between expectation and stimulus. Designers create spaces that are anticipated, but with elements that are off the expectations. There are continuous process between perception and cognition (knowledge) that defines our expectations and fulfillment. It distinguishes, hypothesizes, bridges and replaces the voids.


ART by Paolo Uccello (1397-1475) Innovative use of a geometric algorithm incorporating linear perspective in painting where broken lances run along perspective lines


This is 4th article of 20 topics series on ISSUES for DESIGN


PERCEPTION through SCALES and CONVERSIONS -Issues or Design -3

Post 606 by Gautam Shah 


Our Faculties of Perceptions have inherent limitations. Our capacity of viewing, hearing, tasting or experiencing is within certain range. Beyond this natural range, our body shuts off the mechanism of perception, tones the reception to within the capacity of the body, or convert the sensations to some other form of experience. With certain tools we can enlarge or enhance the comprehension.


Forced Perspective of Gallery at Palazzo Spada Rome by Francesco Borromini 1632 > 8.6 mt long gallery gives illusion of 4 times the length > Wikipedia image by Livioandronico2013

We deal with entities in following order:

  1.  As they really exist in original measures, if in perceptible range.
  2. In their scaled representations, to bring them in a perceptible and manipulable range and for storage.
  3. Experience the imperceptible entities after their conversion to some other form.

Facade of Pantheon Paris -a proposal by Jacques-Germain Soufflo > Wikipedia image


Same Facade of Pantheon Paris with few changes but different light-shade > Wikipedia – Flickr image by besopha

We primarily perceive objects and happenings as they directly affect our sensorial faculties, with whatever their inherent limitations. We experience objects through the sensory affectations like light, colour, sound, temperature, smell, pressure, etc., as caused to our body. But such affectations are very subjective, and not easily accountable to any universal system of measurements. We can, however, emulate the changes elsewhere (as equivalents of physio-chemical-electrical changes in our body) and measure the ‘scale’ sensory affectations. For example, we measure the temperature as it affects the mass of mercury or a metal sensor. This allows measurements of range beyond body’s nominal capacity. Similarly inaudible sounds such as in ‘ultra or infra’ range can also be measured.


Magnetic Resonance Imaging MRI > Wikipedia image by KasugaHuang

Real and Scaled entities need a familiar anchorage to set the orientation or reference. Maps and plans are nominally set to North as upward direction, or building entrance accessed from ‘plan read sides’ such as the bottom-up or right-inward. A sea or vast terrain map, requires a superimposed location matrix of Latitude and Longitude, and often Altitude from the mean sea level. Planetary maps are referenced with some familiar stars or configurations like constellations. Maps are reduced (or enlarged) to include a familiar feature like a coastline.


First Floor Plan of Winn Memorial library Woburn MA USA > Here seen as a flipped over image for a different perception > Wikipedia image

As a designer, a persistent exposure of certain views like plans, elevations, etc. is inevitable. The graphical compositions (of massing of objects, lineal flows, form-shapes, etc.) and their orientation from ‘image-read side’ conditions or rather mesmerizes the designers. To break of this persistency, one needs to re-look at the image by changing its orientation, changing the tonal value of a colour or monochrome image, by altering the scale of the image, by reversing (backside to front) or mirroring the image. Similar conditions arise when dealing with 3D objects like models. Architectural models are small size replicas of larger entities. These are more often than not seen from the top, creating a bias for ‘bird-eye’ view, resulting in articulated detailing of upper sections at the cost of road level specifics. Similarly architectural models deal more with the exteriors, and less to the interior configuration. This is sought to be resolved by placing or inserting ‘scope’ or thin tube-cameras in the lower and interior sections or by CAD aided 3D views.


Model of Marina Bay sands > Wikipedia image by Huaiwei

We record our experiences for posterity over some media, in some scalable version. A scaled and recorded version allow faster access and manipulation while reducing the storage space. A site plan drawn at a smaller scale allows one to comprehend larger extent, or the enlarged detail allows greater attention. Scaling also allows to override or attend to details. Designers are trained to manipulate, arrange, or compose scaled representations, and generally achieve results equal to their real size forms. Small scale models are replicas of the larger-real size object, though with fewer or selective details, and are used for variety of design processes.


For a Designer At any scale Perception remains consistent > Image from Pixabay by geralt

We generate plans and such representations of objects in monochrome colour, not just for the sake of printing economy, but to remove the biassed perception of colours. An ‘equal colour’ image allows for neat spatial experience. Conversely Sciography (=study of shades and shadows cast by simple architectural forms on plane surfaces) is used for accentuating the mass-void configuration. But problems arise due to vastly different results offered by Sciography over coloured versus monochrome objects.


Palais Garnier Entrance > Wikipedia image by Charles Garnier (1825-1898)

Surrogate, Metaphoric and Symbolic Representations: These are perceptions through conversions. Here we deal with complex entities by converting or translating them into Surrogate, Metaphoric and Symbolic representations. Designers work with such representations to achieve their design objectives. We use symbols like parallel line hatching to represent brickwork, trees on a contour map, lightening bar to show high voltage electrical current. Different trades have accepted signs and symbols to represent frequently used objects.


A Thermogram > Wikipedia image by Passivhaus Institute

Graphical Representations: Temperature or heartbeats as represented in a graph chart like a Thermal-gram or a Cardiogram, do not convey anything to a lay person. A written musical scale or stenographer’s phonetic language notes do not recreate the original sound, yet convey the meaning. A graphical representation stands for the original in a restricted sense. Nominally graphical representations are difficult to read, but with frequent exposure, one gains the proficiency to automatically interpret the conveyed information, as if it is the real happening. Such proficiencies are circumstance and person specific, and cannot be replicated everywhere or by everyone. Graphical representations, often create an ‘artistic’, proportionate, or an ‘aesthetic composition’ on their own.


Aviator’s Night vision Imaging system > Wikipedia image by Koalorka at en.wikipedia

In some situations Designers deal with a secondary graphical or scaled formation that represents another graphical or scaled entity. Designers, who deal with a variety of representations, scaled, graphical or metaphoric, are often not aware of the levels of conversions that distance the original. They are also oblivious of the transition from one form of representation to another. It becomes a ‘second nature’ for them. It is only when the desired objectives are not achieved, or when some unusual phenomena are discovered that a designer begins to re-search the process.


This is 3rd article of 20 topics series on ISSUES for DESIGN

INTERVENTIVE SPACES – Issues for Design -2

Post 605 by Gautam Shah 



8511795693_228eb1ec8d_zInterventive spaces are issues of design, as these intervene or interpose in situations or circumstances. The interventions enter or appear, as relevant or irrelevant, intravenous extraneous, features or engagements. The interventions in a space, with an object, natural entity or a being, manifest new space segments. These new segments are intentional as well as circumstantial. The new segments nominally extend to the domain edge, and where such edges are notional, their extent is infinite. The infinite extent is due to the transgressions occurring through the sensual reach like visual, audio, smells etc. The original and the new space segments may not be of the same domain but have primary relationships with the domain edges, and secondary connections among themselves.


Marina city Chicago USA > Wikipedia image by Diego Delso

 ‘You see my five fingers, but somebody can see the five gaps between my fingers. Ordinarily you will not see the gaps, you will see five fingers. But the gaps are more real: fingers may come and go, gaps will remain’. Osho Rajneesh -The Great Pilgrimage from Here to Here.

For spatial or temporal intervention to occur, there is need for presence on two or more ends. A gaps exists only as mid segment.  For two ends to have a meaning the mid space or time gap must have scale, derived from the ends. The space or time gap as a mid segment may not exist in reality but can mark its presence through memories or metaphorically. If the gap is too wide in proportion to the ends’ elements, the mid segment becomes irreverent.

640px-Shaohao_-_temple_courtyard_-_P1050734The siting of a building on a land, be it on the road face, little away per the regulation, or with a deliberate setback, are all intentional space segment formations. Circumstantial conception of intervening space segments occurs as gap, an interlude, an entr’acte between two or more elements. The intermediate spaces exist as a physical distance and also as time transition. In architecture, human settlements, art, performances, expressions and communication, substantial content is of space and time miss-outs. The absence or silence, are the Interludes that defines the spatial experience. The spaces between, buildings, people or other objects, are designed for reinforcing the continuity or enforcing the discontinuity.

Gravity has been omnipresent force and a structure on Earth is gravity stacked and inverted. The spatial (or even temporal) interrelationship with the earth, signifies the stacking (pyramid), the cantilever (inversion) and the ethereal (flying-airborne).


Stockholm > Wikipedia image by Holger.Ellgaard


In Architecture the interludes help spread the mass. The spatial interludes are in the form of distance between buildings and sections of it, Chowks, setbacks and offsets. Buildings are spaced, where the adjoining mass is repetition (same), smaller or larger, but spatial connection is within a bridging distance. The bridging is aided by visual clues such as proportions, form, scale, texture, colour, directionality and the context of perception (perspective, framing, referencing clues, etc.), foreground-background relationship. Other relevancies include, participation of humans and interactions with objects, sequencing, hierarchies, patterns, styling-orientation and connection to the environmental elements.


At micro level Architectonic elements occupy the building spaces and surfaces by forming orders, series, and harmonics. In all these the intervening element, the gap-spaces reveal the underlying sub-face. The intervening elements, such as openings, columns, corners, shapes, projections and recesses, textures, colours, light-shade and other transgressions create the time and space matrices.


Street of Ponto Cho Kyoto Japan > Wikipedia-Flickr image by Masahiro Hayata

Human settlements have interludes formed between built forms. The form, purpose and its bridges with built spaces, however, well-planned, never persist. It changes with little innovations here and there. But the relationship, between ‘something (engagement) and nothing’, creates the settlement. Chowks, plazas, streets, roads, gardens, playgrounds, cemeteries, are juxtaposed against the built spaces. Each window of the house offers a different view. Each porch has a unique setting. Each dwelling has unique set of ‘sounds, smells, air and feel due to varied intervening spaces’.

Tenement Yard


The temporal interventions relate to time, and so the movement, such as time required for image grabbing, visual scanning, travel time clues such as milestones, scaling through perspective. The movement attests to slopes (accelerations) and rises (decelerators). The flicker of an eye is a gap large enough to ignore the frame edge and prepare for the subsequent reflection.


Film Strip > Wikipedia image by Bart from New Orleans USA

Expressions and Communications exploit these dualities or multiplicity. We express, through sounds, gestures, postures, movement and through spoken language. And to these are added, the colour, texture, illumination, sets. The gestures and postures become relevant through the change, marked by the transition time to shift from one to another. One can stretch or shorten the period and modulate the expression. In absentia communications such as telephony, audio-video recordings, modulate the scope of expression. To suppress the data band width requirements, the quality is depressed into narrow channels. But in spite of these, the spatial and temporal interludes are not affected. In some long distance communications the transition of up and down signals occur on the same channel, and so one misses the ‘quick-response’ or feedback experience.


Melodramatic scene > ART by Raja Ravi Verma > from play Raja Harishchandra (India)

In case of language, spoken or written, it is the space between the words that marks the interlude, a silence, as Lao-tse says ‘a wheel is the space between the spokes‘. Melodrama has words spoken over the music, but in Opera the words and music each other, respecting the individual need for ‘the break or absence’. In later day the drama, the music is sparingly used, only to distance the actions, or back up the silent actions or mime. In Cinema, the narrative is of presence and absence of the characters. The absence (and often the presence is doctored) is filled in with music or noise. It may be a ticking sound to mark the passage of time or echoes or reverberations to mark the scale of the physical space.


Scene from Double Indemnity 1944 > Wikipedia image

In the Realm of music, the presence of the played sound, the absence of it (interlude, silence, the ‘rests’, or ‘Khali in Taal’ or beats), and incidental noises (reverberations, echoes, background noise seepage), all together forms the musical texture. These are intentionally created by the musician, the architecture of the place and involvement of the listener. The listener, through recent and past memories, join all the fragments, even in actual absence of it.

Playing Taal by Hand

Playing Taal by hand > Wikipedia image by Badagnani

‘Between sounds of music there are gaps of silence. The authentic music consists not of sounds, but of the gaps. Sounds come and go; those gaps remain. And music can make you aware of those gaps more beautifully than anything else; hence I have to say that music comes next to silence. But it is possible even the musician may not be aware of it, unless his music is his meditation too. Then, soon, the shift from sounds to silence’. -Osho Rajneesh The Great Pilgrimage from Here to Here.


Music Rests or spaces > Wikipedia image by Marmelad

Artworks are select perspectives that reveal connect between environment, buildings and people. The spaces between them are modulated by colour, size, depth of view, referential elements, framing and story content. In primitive cave-art it is the space between them and the form of the figures that created the stage. A stage, where each element is sited and interconnected.


The space of silence and absence of time are not amorphous. These forms, manifest differently in different contexts, real and dreams. The Interventive time and space reinforce the continuity or enforce the discontinuity.


National Congress Brazil, By Oscar Niyemeyer Wikipedia Flickr image by Marcelo Jorge Vieira from Brazil

This is 2nd article of 20 topics on ISSUES for DESIGN (


Post 604 by Gautam Shah 



Percussion 20070727-beleuvenissen-gocoo-11

Percussive word derives from (Latin 1735) percuss, past participle stem of percutere. Percussion is a motion formed by striking, such as a beating, pounding or hammering, versus just vibration. In phonetics it is the sound of smacking the lips or gnashing the teeth. Percussive dances have highly rhythmic movement like tapping feet, clapping, or finger snapping, etc.



Percussive tools deliver concentrated blows or impact. The delivery is in swift motion at specific location generating or transmitting a force. The tools can have ‘a nonspecific end’ or sharper point or edge as specific function end. The self weight of the impacting end delivers the mass, and the holding arm or the tool handle adds to the momentum while controlling the velocity. The ‘sharpness’ of the impact is determined by the type of task, which in turn is defined by the deformation required in the material. To beat flour dough or wet clay requires very little force, but to deform copper or iron greater impact is required.


Roof-slate workers hammer > Wikipedia image by Antoine Taveneaux


The percussive hand tools operate on circular motion, where the handle or arm form a swinging arc to deliver the blow. In hand tools the length of an axis (radius) is formed by the combined measures of the handle and the operative arm. In case of machines, the handle is the ‘arm’. Percussive tools also use the pull of the gravity as a work force, such as for driving piles for foundation work.



Percussive tools have been of basic two types: The impacting ones with own head formations (axes pounder, beetle, mallet, maul, pestle, sledge, or with separate work points or edges. Percussive tools work as combination of head weight and handle length. Different combinations are used for craft to industrial work. Goldsmiths use light-head and long-armed hammers. A stone mason uses a heavy metal-head and small handle. For metal forging, the hammers have heavy-head and long-arm. A long handle, even if not needed for impact, it helps to control the blows reduces work fatigue. Soft headed percussive tools are used for sheet metal fabrication, painted elements, fabric leveling, etc.


Spears and Handles > Wikipedia image

HAMMERS: A hammer is a striking tool also known as a pounder, beetle, mallet, maul, pestle, sledge, etc. There are many trade specific hammers, like, the carpenter’s claw type, smith’s rivetting, boiler-maker’s, bricklayer’s, blacksmith’s, machinist’s ball peen and cross peen, goldsmiths’, smith’s stone (or spalling), prospecting, and tacks hammer. Each hammer has a distinctive form, with minor variations in terms of weight, length and angle of the handle, and the shape of the face. A pounder, or hammer stone, was the first tool to have a handle, marking a great technological advance. A long handle, even if not needed for dynamic effect (as in a tool used only for light blows), makes the tool easier to control and generally reduces operators’ fatigue. Club like pounders or mallet, with handles of the same material are widely used. The hammer as a tool, for nailing, rivetting, and smithing, originated in the Metal Age. For beating lumps of metal into strips and sheet, heavy and compact hammers with flat faces are needed, whereas lighter ones are more suited to rivetting and driving nails and wooden pegs.


Few Hammer heads > Flickr image by denise carbonell

Hammers with dual heads are in use since Roman age. Hammers with dual heads include: clawed hammers for pulling out nails, hammers with a chisel or pointed ends to dig out shafts, toothed edges to smoothen the stone surfaces. Other special forms of the peen (-the end opposite the flat face) like hemispherical, round-edged, and wedge like shapes helped the metalworker stretch and bend metal or the mason to chip or break stone or bricks. A file maker’s hammer has two chisel-like heads, to score flat pieces of lead (file blanks) that were subsequently hardened by heating and quenching. Heavy hammers are used as part of power tools, and largest are the pile drivers. Trip-hammers are gravity impulse based but steam hammers use, besides gravity a downward thrust from a steam-pushed piston. Pneumatic hammers driven by air include the hammer drill, used on rock and concrete. The rivetting hammer is used in steel construction with girders and plates.


Forging hammer > Wikipedia image by Vitold Muratov

Hammers’ heads are meant to impact the task pieces by striking over the head of a chisel, nails, shank, pins, bars, shaping dies, etc.


Forging gang > Wikipedia image by Lord van Tasm

CHISELS: Chisels have been the chief cutting tools often combined with a hammering device. Chipped flints were used in 8000 BC, till neolithic period. Rectangular flint and obsidian chisels were used on soft stone and timber. Chisels with concave heads were used to create deeper sections. Chisels and gouges of very hard stone were used to dig out the bowls out of soft stones such as alabaster, gypsum, soapstone, and volcanic rock. The earliest copper and bronze chisels were long compared to flint chisels, and were used by the Egyptians to dress limestone and sandstone for their monuments. Use of wooden handles saved the chisel metal to half length, while causing less damage to the mallet. The chisel has since then taken on many shapes, and is being put to many different uses.


Modern day machines incorporate percussive processes. Forging workshops use automatic forging machines. Construction sites use pneumatic pile driving devices. Industrial presses use percussion as metal cutting, shaping, forming device. Stamping machine impact shaping or forming dies to generate a shaped product like coins. Gold foil makers beat small pieces of gold between layers of leathers.



Cricket bat a striking or percussive device > Street cricket Agra Uttar Pradesh India Flicker image by John Haslam