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A trip hammer, also known as a tilt hammer or helve hammer, is a massive powered
hammer A hammer is a tool, most often a hand tool, consisting of a weighted "head" fixed to a long handle that is swung to deliver an impact to a small area of an object. This can be, for example, to drive nails into wood, to shape metal (as wi ...
. Traditional uses of trip hammers include pounding, decorticating and polishing of grain in
agriculture Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people ...
. In
mining Mining is the extraction of valuable minerals or other geological materials from the Earth, usually from an ore body, lode, vein, seam, reef, or placer deposit. The exploitation of these deposits for raw material is based on the econom ...
, trip hammers were used for crushing metal ores into small pieces, although a
stamp mill A stamp mill (or stamp battery or stamping mill) is a type of mill machine that crushes material by pounding rather than grinding, either for further processing or for extraction of metallic ores. Breaking material down is a type of unit operati ...
was more usual for this. In finery forges they were used for drawing out blooms made from
wrought iron Wrought iron is an iron alloy with a very low carbon content (less than 0.08%) in contrast to that of cast iron (2.1% to 4%). It is a semi-fused mass of iron with fibrous slag inclusions (up to 2% by weight), which give it a wood-like "grain" ...
into more workable bar iron. They were also used for fabricating various articles of
wrought iron Wrought iron is an iron alloy with a very low carbon content (less than 0.08%) in contrast to that of cast iron (2.1% to 4%). It is a semi-fused mass of iron with fibrous slag inclusions (up to 2% by weight), which give it a wood-like "grain" ...
, latten (an early form of
brass Brass is an alloy of copper (Cu) and zinc (Zn), in proportions which can be varied to achieve different mechanical, electrical, and chemical properties. It is a substitutional alloy: atoms of the two constituents may replace each other wi ...
),
steel Steel is an alloy made up of iron with added carbon to improve its strength and fracture resistance compared to other forms of iron. Many other elements may be present or added. Stainless steels that are corrosion- and oxidation-resistan ...
and other metals. One or more trip hammers were set up in a
forge A forge is a type of hearth used for heating metals, or the workplace (smithy) where such a hearth is located. The forge is used by the smith to heat a piece of metal to a temperature at which it becomes easier to shape by forging, or to th ...
, also known variously as a hammer mill, hammer forge or hammer works. The hammers were usually raised by a cam and then released to fall under the force of
gravity In physics, gravity () is a fundamental interaction which causes mutual attraction between all things with mass or energy. Gravity is, by far, the weakest of the four fundamental interactions, approximately 1038 times weaker than the stro ...
. Historically, trip hammers were often powered
hydraulically Hydraulics (from Greek: Υδραυλική) is a technology and applied science using engineering, chemistry, and other sciences involving the mechanical properties and use of liquids. At a very basic level, hydraulics is the liquid counte ...
by a
water wheel A water wheel is a machine for converting the energy of flowing or falling water into useful forms of power, often in a watermill. A water wheel consists of a wheel (usually constructed from wood or metal), with a number of blades or buckets ...
. Trip hammers are known to have been used in
Imperial China The earliest known written records of the history of China date from as early as 1250 BC, from the Shang dynasty (c. 1600–1046 BC), during the reign of king Wu Ding. Ancient historical texts such as the '' Book of Documents'' (early chapt ...
since the
Western Han dynasty The Han dynasty (, ; ) was an imperial dynasty of China (202 BC – 9 AD, 25–220 AD), established by Liu Bang (Emperor Gao) and ruled by the House of Liu. The dynasty was preceded by the short-lived Qin dynasty (221–207 BC) and a war ...
. They also existed in the contemporary
Greco-Roman world The Greco-Roman civilization (; also Greco-Roman culture; spelled Graeco-Roman in the Commonwealth), as understood by modern scholars and writers, includes the geographical regions and countries that culturally—and so historically—were dir ...
, with more evidence of their use in
medieval Europe In the history of Europe, the Middle Ages or medieval period lasted approximately from the late 5th to the late 15th centuries, similar to the post-classical period of global history. It began with the fall of the Western Roman Empire a ...
during the 12th century. During the
Industrial Revolution The Industrial Revolution was the transition to new manufacturing processes in Great Britain, continental Europe, and the United States, that occurred during the period from around 1760 to about 1820–1840. This transition included going f ...
the trip hammer fell out of favor and was replaced with the power hammer. Often multiple hammers were powered via a set of
line shaft A line shaft is a power-driven rotating shaft for power transmission that was used extensively from the Industrial Revolution until the early 20th century. Prior to the widespread use of electric motors small enough to be connected directly t ...
s, pulleys and belts from a centrally located power supply.


Early history


China

In ancient China, the trip hammer evolved out of the use of the
mortar and pestle Mortar and pestle is a set of two simple tools used from the Stone Age to the present day to prepare ingredients or substances by crushing and grinding them into a fine paste or powder in the kitchen, laboratory, and pharmacy. The ''mortar'' ( ...
, which in turn gave rise to the treadle-operated tilt-hammer ( Chinese: 碓
Pinyin Hanyu Pinyin (), often shortened to just pinyin, is the official romanization system for Standard Mandarin Chinese in China, and to some extent, in Singapore and Malaysia. It is often used to teach Mandarin, normally written in Chinese fo ...
: ''dui''; Wade-Giles: ''tui'').Needham, Volume 4, Part 2, 183. The latter was a simple device employing a lever and fulcrum (operated by pressure applied by the weight of one's foot to one end), which featured a series of catches or lugs on the main revolving shaft as well.Needham, Volume 4, Part 2, 390. This device enabled the labor of pounding, often in the decorticating and polishing of grain, and avoided manual use of pounding with hand and arm. Although Chinese historians assert that its origins may span as far back as the
Zhou Dynasty The Zhou dynasty ( ; Old Chinese ( B&S): *''tiw'') was a royal dynasty of China that followed the Shang dynasty. Having lasted 789 years, the Zhou dynasty was the longest dynastic regime in Chinese history. The military control of China by th ...
(1050 BC–221 BC), the British sinologist
Joseph Needham Noel Joseph Terence Montgomery Needham (; 9 December 1900 – 24 March 1995) was a British biochemist, historian of science and sinologist known for his scientific research and writing on the history of Chinese science and technology, i ...
regards the earliest texts to describe the device are the '' Jijiupian'' dictionary of 40 BC, Yang Xiong's text known as the '' Fangyan'' of 15 BC, as well as the "best statement" the ''Xin Lun'' written by Huan Tan about 20 AD (during the usurpation of
Wang Mang Wang Mang () (c. 45 – 6 October 23 CE), courtesy name Jujun (), was the founder and the only emperor of the short-lived Chinese Xin dynasty. He was originally an official and consort kin of the Han dynasty and later seized the th ...
).Needham, Volume 4, Part 2, 184. The latter book states that the legendary mythological king known as Fu Xi was the one responsible for the pestle and mortar (which evolved into the tilt-hammer and then trip hammer device). Although the author speaks of the mythological Fu Xi, a passage of his writing gives hint that the waterwheel and trip-hammer were in widespread use by the 1st century AD in China (for water-powered Chinese
metallurgy Metallurgy is a domain of materials science and engineering that studies the physical and chemical behavior of metallic elements, their inter-metallic compounds, and their mixtures, which are known as alloys. Metallurgy encompasses both the sc ...
, see Du Shi):
Fu Hsi invented the pestle and mortar, which is so useful, and later on it was cleverly improved in such a way that the whole weight of the body could be used for treading on the tilt-hammer (tui), thus increasing the efficiency ten times. Afterwards the power of animals—donkeys, mules, oxen, and horses—was applied by means of machinery, and water-power too used for pounding, so that the benefit was increased a hundredfold.Needham, Volume 4, Part 2, 392.
However, this passage as well as other early references from the Han era may rather refer to a water lever, not a trip hammer. Later research, pointing to two contemporary Han era funeral wares depicting hydraulic hammers, proved that vertical waterwheels were used to power batteries of trip hammers during the Han dynasty. With his description, it is seen that the out-of-date Chinese term for pestle and mortar (dui, tui) would soon be replaced with the Chinese term for the water-powered trip-hammer (. The
Han Dynasty The Han dynasty (, ; ) was an Dynasties in Chinese history, imperial dynasty of China (202 BC – 9 AD, 25–220 AD), established by Emperor Gaozu of Han, Liu Bang (Emperor Gao) and ruled by the House of Liu. The dynasty was preceded by th ...
scholar and poet
Ma Rong Ma Rong (; 79–166), courtesy name Jichang (), was a Chinese poet and politician of the Eastern Han dynasty. He was born in Youfufeng () in the former Han capital region, in modern Xianyang, Shaanxi Province. His father Ma Yan (马严) was a ...
(79–166 AD) mentioned in one of his poems of hammers 'pounding in the water-echoing caves'. As described in the '' Hou Han Shu'', in 129 AD the official
Yu Xu Yu Xu (; March 1986 – November 12, 2016) was a Chinese female fighter pilot who served as a flight squadron leader in the August 1st aerobatic team of the People's Liberation Army Air Force. Early life Yu was born in Chengdu, the capital o ...
gave a report to Emperor Shun of Han that trip hammers were being exported from Han China to the Western
Qiang people The Qiang people ( Qiangic: ''Rrmea''; ) are an ethnic group in China. They form one of the 56 ethnic groups officially recognised by the People's Republic of China, with a population of approximately 310,000 in 2000. They live mainly in a ...
by way of canals through the Qilian Mountains. In his ''Rou Xing Lun'', the government official
Kong Rong Kong Rong () (153 – 26 September 208), courtesy name Wenju, was a Chinese poet, politician, and minor warlord. who lived during the late Eastern Han dynasty of China. He was a 20th generation descendant of Confucius. As he was once the Chance ...
(153–208 AD) remarked that the invention of the trip hammer was an excellent example of a product created by intelligent men during his own age (comparing the relative achievements of the sages of old). During the 3rd century AD, the high government official and engineer
Du Yu Du Yu (223– January or February 285), courtesy name Yuankai, was a Chinese classicist, military general, and politician of the state of Cao Wei during the late Three Kingdoms period and early Jin dynasty. Life Du Yu was from Duling County ...
established the use of combined trip hammer batteries (lian zhi dui), which employed several shafts that were arranged to work off one large waterwheel.Needham, Volume 4, Part 2, 393. In Chinese texts of the 4th century, there are written accounts of men possessing and operating hundreds of trip hammer machines, such as the venerable mathematician Wang Rong (died 306 AD), Deng Yu (died 326 AD), and Shi Chong (died 300 AD), responsible for the operation of hundreds of trip hammers in over thirty governmental districts throughout China.Needham, Volume 4, Part 2, 392-393. There are numerous references to trip hammers during the
Tang Dynasty The Tang dynasty (, ; zh, t= ), or Tang Empire, was an Dynasties in Chinese history, imperial dynasty of China that ruled from 618 to 907 AD, with an Zhou dynasty (690–705), interregnum between 690 and 705. It was preceded by the Sui dyn ...
(618–907 AD) and
Song Dynasty The Song dynasty (; ; 960–1279) was an imperial dynasty of China that began in 960 and lasted until 1279. The dynasty was founded by Emperor Taizu of Song following his usurpation of the throne of the Later Zhou. The Song conquered the res ...
(960–1279), and there are
Ming Dynasty The Ming dynasty (), officially the Great Ming, was an Dynasties in Chinese history, imperial dynasty of China, ruling from 1368 to 1644 following the collapse of the Mongol Empire, Mongol-led Yuan dynasty. The Ming dynasty was the last ort ...
(1368–1644) references that report the use of trip hammers in papermills of
Fujian Fujian (; alternately romanized as Fukien or Hokkien) is a province on the southeastern coast of China. Fujian is bordered by Zhejiang to the north, Jiangxi to the west, Guangdong to the south, and the Taiwan Strait to the east. Its ...
Province.Needham, Volume 4, Part 2, 394. Although Chinese trip hammers in China were sometimes powered by the more efficient vertical-set waterwheel, the Chinese often employed the horizontal-set waterwheel in operating trip hammers, along with recumbent hammers.Needham, Volume 4, Part 2, 391–392. The recumbent hammer was found in Chinese illustrations by 1313 AD, with the publishing of Wang Zhen's ''Nong Shu'' book on ancient and contemporary (medieval) metallurgy in China.Needham, Volume 4, Part 2, 395. There were also illustrations of trip hammers in an encyclopedia of 1637, written by Song Yingxing (1587–1666).Song, 91–93. The Chinese use of the cam remained confined to the horizontal type and was limited to a "small variety of machines" that included only rice hulling and much later mica-pounders, paper mills and saw mills, while fulling stocks, ore stamps or forge hammers were unknown.


Europe


Greco-Roman world

The main components for water-powered trip hammers –
water wheel A water wheel is a machine for converting the energy of flowing or falling water into useful forms of power, often in a watermill. A water wheel consists of a wheel (usually constructed from wood or metal), with a number of blades or buckets ...
s, cams, and hammers – were already known in Hellenistic times. Early cams are in evidence in water-powered automata from the third century BC. One Greek automaton in particular, a
flute The flute is a family of classical music instrument in the woodwind group. Like all woodwinds, flutes are aerophones, meaning they make sound by vibrating a column of air. However, unlike woodwind instruments with reeds, a flute is a reedles ...
player whose mechanism was described by the Banu Musa but can be "reasonably" attributed to Apollonius of Perge, functions on the principle of water-powered trip hammers. The
Roman Roman or Romans most often refers to: * Rome, the capital city of Italy * Ancient Rome, Roman civilization from 8th century BC to 5th century AD *Roman people, the people of ancient Rome *''Epistle to the Romans'', shortened to ''Romans'', a lett ...
scholar Pliny ('' Natural History'' 18.97) indicates that water-driven pestles had become fairly widespread in
Italy Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical ...
by the first century AD: While some scholars have viewed this passage to mean a watermill, recent scholarship argues that ''mola'' must refer to water-powered trip hammers which were used for the pounding and hulling of
grain A grain is a small, hard, dry fruit ( caryopsis) – with or without an attached hull layer – harvested for human or animal consumption. A grain crop is a grain-producing plant. The two main types of commercial grain crops are cereals and legum ...
. Their mechanical character is also suggested by an earlier reference of
Lucius Pomponius Lucius Pomponius (fl. c. 90 BC or earlier) was a Roman dramatist. Called ''Bononiensis'' (“native of Bononia” (i.e. Bologna), Pomponius was a writer of Atellanae Fabulae (Atellan Fables), and a near contemporary of Quintus Novius. Pomponius ...
(fl. 100-85 BC) to a fuller's mill, a type of mill that has been operated at all times with falling stocks. However, it has been pointed out by recent scholarship that the translation of Pomponius' fragmentary text could be faulty, and relies on translating "mola", which is often thought to mean either a mill or millstone, to instead refer to a water powered trip hammer. Grain-pounders with pestles, as well as ordinary
watermill A watermill or water mill is a mill that uses hydropower. It is a structure that uses a water wheel or water turbine to drive a mechanical process such as milling (grinding), rolling, or hammering. Such processes are needed in the production ...
s, are attested as late as the middle of the 5th century AD in a
monastery A monastery is a building or complex of buildings comprising the domestic quarters and workplaces of monastics, monks or nuns, whether living in communities or alone (hermits). A monastery generally includes a place reserved for prayer whic ...
founded by Romanus of Condat in the remote
Jura region The Jura Mountains ( , , , ; french: Massif du Jura; german: Juragebirge; it, Massiccio del Giura, rm, Montagnas da Jura) are a sub-alpine mountain range a short distance north of the Western Alps and mainly demarcate a long part of the Frenc ...
, indicating that the knowledge of trip hammers continued into the early
Middle Ages In the history of Europe, the Middle Ages or medieval period lasted approximately from the late 5th to the late 15th centuries, similar to the post-classical period of global history. It began with the fall of the Western Roman Empire ...
. At the Italian site of Saepinum excavators have recently unearthed a late antique water mill that may have employed trip hammers for tanning, the earliest evidence of its kind in a classical context. The widest application of trip hammers seems to have occurred in Roman mining, where ore from deep veins was first crushed into small pieces for further processing. Here, the regularity and spacing of large indentations on stone
anvil An anvil is a metalworking tool consisting of a large block of metal (usually forged or cast steel), with a flattened top surface, upon which another object is struck (or "worked"). Anvils are as massive as practical, because the higher ...
s indicate the use of cam-operated ore stamps, much like the devices of later
medieval In the history of Europe, the Middle Ages or medieval period lasted approximately from the late 5th to the late 15th centuries, similar to the post-classical period of global history. It began with the fall of the Western Roman Empire a ...
mining.Barry C. Burnham: "Roman Mining at Dolaucothi: The Implications of the 1991-3 Excavations near the Carreg Pumsaint", ''Britannia'', Vol. 28 (1997), pp. 325-336 (333-335) Such mechanically deformed anvils have been found at numerous Roman silver and gold mining sites in
Western Europe Western Europe is the western region of Europe. The region's countries and territories vary depending on context. The concept of "the West" appeared in Europe in juxtaposition to "the East" and originally applied to the ancient Mediterranean ...
, including at Dolaucothi (
Wales Wales ( cy, Cymru ) is a country that is part of the United Kingdom. It is bordered by England to the east, the Irish Sea to the north and west, the Celtic Sea to the south west and the Bristol Channel to the south. It had a population in ...
), and on the
Iberian peninsula The Iberian Peninsula (), ** * Aragonese and Occitan: ''Peninsula Iberica'' ** ** * french: Péninsule Ibérique * mwl, Península Eibérica * eu, Iberiar penintsula also known as Iberia, is a peninsula in southwestern Europe, def ...
, where the datable examples are from the 1st and 2nd century AD. At Dolaucothi, these trip-hammers were hydraulic-driven and possibly also at other Roman mining sites, where the large-scale use of the hushing and ground sluicing technique meant that large amounts of water were directly available for powering the machines. However, none of the Spanish and Portuguese anvils can be convincingly associated with mill sites, though most mines had water sources and leat systems which could easily be harnessed. Likewise, the dating of the Pumsaint stone to the Roman era did not address that the stone could have been moved, and relies on a series of interlinked probabilities which would jeopardize the conclusion of a Roman dating should any of them unravel.


Medieval Europe

Water-powered and mechanised trip hammers reappeared in
medieval Europe In the history of Europe, the Middle Ages or medieval period lasted approximately from the late 5th to the late 15th centuries, similar to the post-classical period of global history. It began with the fall of the Western Roman Empire a ...
by the 12th century. Their use was described in medieval written sources of
Styria Styria (german: Steiermark ; Serbo-Croatian and sl, ; hu, Stájerország) is a state (''Bundesland'') in the southeast of Austria. With an area of , Styria is the second largest state of Austria, after Lower Austria. Styria is bordered ...
(in modern-day Austria), written in 1135 and another in 1175 AD.Needham, Volume 4, Part 2, 379. Medieval French sources of the years 1116 and 1249 both record the use of mechanised trip hammers used in the forging of
wrought iron Wrought iron is an iron alloy with a very low carbon content (less than 0.08%) in contrast to that of cast iron (2.1% to 4%). It is a semi-fused mass of iron with fibrous slag inclusions (up to 2% by weight), which give it a wood-like "grain" ...
. Medieval European trip hammers by the 15th century were most often in the shape of the vertical pestle stamp-mill, although they employed more frequent use of the vertical waterwheel than earlier Chinese versions (which often used the horizontal waterwheel). The well-known
Renaissance The Renaissance ( , ) , from , with the same meanings. is a period in European history marking the transition from the Middle Ages to modernity and covering the 15th and 16th centuries, characterized by an effort to revive and surpass ide ...
artist and inventor
Leonardo da Vinci Leonardo di ser Piero da Vinci (15 April 14522 May 1519) was an Italian polymath of the High Renaissance who was active as a painter, draughtsman, engineer, scientist, theorist, sculptor, and architect. While his fame initially rested on ...
often sketched trip hammers for use in forges and even file-cutting machinery, those of the vertical pestle stamp-mill type. The oldest depicted European illustration of a forge-hammer is perhaps the
A Description of the Northern Peoples ''Historia de Gentibus Septentrionalibus'' was a monumental work by Olaus Magnus on the Nordic countries, printed in Rome 1555. It was a work which long remained for the rest of Europe the authority on Swedish matters. Its popularity increase ...
of Olaus Magnus, dated to 1565 AD. In this woodcut image, there is the scene of three martinets and a waterwheel working wood and leather bellows of the Osmund Bloomery furnace. The recumbent hammer was first depicted in European artwork in an illustration by Sandrart and Zonca (dated 1621 AD).


Types

A trip hammer has the head mounted at the end of a recumbent helve, hence the alternative name of helve hammer. The choice of which type was used in a particular context may have depended on the strain that its operation imposed on the helve. This was normally of wood, mounted in a cast iron ring (called the hurst) where it pivoted. However, in the 19th century the heaviest helves were sometimes a single casting, incorporating the hurst. The tilt hammer or tail helve hammer has a pivot at the centre of the helve on which it is mounted, and is lifted by pushing the opposite end to the head downwards. In practice, the head on such hammers seems to have been limited to one hundredweight (about 50 kg), but a very rapid stroke rate was possible. This made it suitable for drawing iron down to small sizes suitable for the cutlery trades. There were therefore many such forges known as 'tilts' around
Sheffield Sheffield is a city in South Yorkshire, England, whose name derives from the River Sheaf which runs through it. The city serves as the administrative centre of the City of Sheffield. It is historically part of the West Riding of Yorkshire ...
. They were also used in
brass Brass is an alloy of copper (Cu) and zinc (Zn), in proportions which can be varied to achieve different mechanical, electrical, and chemical properties. It is a substitutional alloy: atoms of the two constituents may replace each other wi ...
battery works for making brass (or copper) pots and pans. In battery works (at least) it was possible for one power source to operate several hammers. In Germany, tilt hammers of up to 300 kg were used in hammer mills to forge iron. Surviving, working hammers, powered by water wheels, may be seen, for example, at the
Frohnauer Hammer The Frohnauer Hammer is an historic hammer mill in Frohnau, a village in the municipality of Annaberg-Buchholz in the Ore Mountains of southeast Germany. The mill is an important witness to proto-industrial development in the Ore Mountains. O ...
in the Ore Mountains. The belly helve hammer was the kind normally found in a finery forge, used for making
pig iron Pig iron, also known as crude iron, is an intermediate product of the iron industry in the production of steel which is obtained by smelting iron ore in a blast furnace. Pig iron has a high carbon content, typically 3.8–4.7%, along with ...
into forgeable bar iron. This was lifted by cams striking the helve between the pivot and the head. The head usually weighed quarter of a ton. This was probably the case because the strain on a wooden helve would have been too great if the head were heavier. The nose helve hammer seems to have been unusual until the late 18th or early 19th century. This was lifted beyond the head. Surviving nose helves and those in picturesFor example in the metalwork gallery in Birmingham Museum & Art Gallery appear to be of cast iron.


Demise

The steam-powered drop hammer replaced the trip hammer (at least for the largest forgings). James Nasmyth invented it in 1839 and
patent A patent is a type of intellectual property that gives its owner the legal right to exclude others from making, using, or selling an invention for a limited period of time in exchange for publishing an enabling disclosure of the invention."A ...
ed in 1842. However, by then forging had become less important for the iron industry, following the improvements to the rolling mill that went along with the adoption of puddling from the end of the 18th century. Nevertheless, hammers continued to be needed for shingling.


See also

* Abbeydale Industrial Hamlet * Dorfchemnitz Iron Hammer Mill *
Finch Foundry Finch Foundry is a 19th-century water-powered forge situated in the village of Sticklepath near Okehampton, Devon, England. It was originally used to produce agricultural and mining hand tools and at its peak produced around 400 edge-tools a da ...
* Freibergsdorf Hammer Mill * Frohnauer Hammer Mill


References


Bibliography

* *Sim, David and Ridge, Isable: "Iron for the Eagles" (2002) *Burnham, Barry C.: "Dolaucothi-Pumsaint: Survey and Excavations at a Roman Gold-mining Complex" (2004) * *Needham, Joseph; Wang, Ling. (1986)
965 Year 965 ( CMLXV) was a common year starting on Sunday (link will display the full calendar) of the Julian calendar. Events By place Byzantine Empire * Arab–Byzantine War: Emperor Nikephoros II conquers the fortress cities of Ta ...
''Science and Civilization in China: Volume 4, Physics and Physical Technology, Part 2, Mechanical Engineering''. Taipei: Caves Books Ltd (reprint edition of Cambridge & New York: Cambridge University Press). . * * *Song, Yingxing, translated with preface by E-Tu Zen Sun and Shiou-Chuan Sun: ''T'ien-Kung K'ai-Wu: Chinese Technology in the Seventeenth Century''. (University Park: Pennsylvania State University Press 1966). * *


External links

* {{DEFAULTSORT:Trip Hammer Articles containing video clips Chinese inventions Hammers Metalworking tools Power hammers