Luigi Aloisio Galvani was an Italian physician, physicist and philosopher, who discovered animal electricity. He is recognized as the pioneer of bioelectromagnetics, in 1780, he discovered that the muscles of dead frogs legs twitched when struck by an electrical spark. This was one of the first forays into the study of bioelectricity, Luigi Galvani was born to Domenico and Barbara Foschi, in Bologna, Papal State. Domenico was a goldsmith and Barbara was his fourth wife and his family was not aristocratic, but they could afford to send at least one of their sons to study at a university. At first Galvani wished to enter the church, so he joined a religious institution, Oratorio dei Padri Filippini, at 15 years old. He planned to take vows, but his parents persuaded him not to do so. Around 1755, Galvani entered the Faculty of the Arts of the University of Bologna, Galvani attended the medicine course, which lasted four years, and was characterized by its bookish teaching. Texts that dominated this course were by Hippocrates, another discipline Galvani learned alongside medicine was surgery.
He learned the theory and the practice and this part of his biography is typically overlooked, but it helped with his experiments with animals and helped familiarize Galvani with the manipulation of a living body. In 1759, Galvani graduated with degrees in medicine and philosophy and he applied for a position as a lecturer at the university. Part of this required him to defend his thesis on 21 June 1761. In the following year,1762, he became a permanent anatomist of the university and was appointed lecturer of surgery. That same year he married Lucia Galeazzi, daughter of one of his professors, Galvani moved into the Galeazzi house and helped with his father-in-laws research. When Galeazzi died in 1775, Galvani was appointed professor and lecturer in Galeazzis place, Galvani moved from the position of lecturer of surgery to theoretical anatomy and obtained an appointment at the Academy of Sciences in 1776. His new appointment consisted of the teaching of anatomy, which was conducted by human dissection.
As a Benedectine member of the Academy of Sciences, Galvani had specific responsibilities and his main responsibility was to present at least one research paper every year at the Academy, which Galvani did until his death. There was a publication that collected a selection of the memoirs presented at the institution and was sent around to main scientific academies. However, since was so slow, sometimes there were debates on priority of the topics used
Wire rope is rope made from wire. It consists of several strands of metal wire laid into a helix, initially wrought iron wires were used, but today steel is the main material used for wire ropes. Historically wire rope evolved from wrought iron chains, which had a record of mechanical failure. While flaws in chain links or solid steel bars can lead to catastrophic failure, friction between the individual wires and strands, as a consequence of their twist, further compensates for any flaws. Wire ropes were developed starting with mining hoist applications in the 1830s, Wire ropes are used dynamically for lifting and hoisting in cranes and elevators, and for transmission of mechanical power. Wire rope is used to transmit force in mechanisms, such as a Bowden cable or the control surfaces of an airplane connected to levers. Also, aircraft cables are available in smaller diameters than wire rope, for example, aircraft cables are available in 3/64 in. Diameter while most wire ropes begin at a 1/4 in, static wire ropes are used to support structures such as suspension bridges or as guy wires to support towers.
An aerial tramway relies on wire rope to support and move cargo overhead, modern wire rope was invented by the German mining engineer Wilhelm Albert in the years between 1831 and 1834 for use in mining in the Harz Mountains in Clausthal, Lower Saxony, Germany. It was quickly accepted because it proved superior to ropes made of hemp or to metal chains, Wilhelm Alberts first ropes consisted of three strands consisting of four wires each. In 1840, Scotsman Robert Stirling Newall improved the process further, the decades were witness to a burgeoning increase in deep shaft mining in both Europe and North America as surface mineral deposits were exhausted and miner had to chase layers along inclined layers. To drive their first shafts into lower slopes beginning Lansford and its Schuylkill County twin-town Coaldale, the German engineering firm of Adolf Bleichert & Co. was founded in 1874 and began to build bicable aerial tramways for mining in the Ruhr Valley. Adolf Bleichert & Co. went on to hundreds of aerial tramways around the world, from Alaska to Argentina, Australia.
The Bleichert company built hundreds of aerial tramways for both the Imperial German Army and the Wehrmacht, in the last half of the 19th century, wire rope systems were used as a means of transmitting mechanical power including for the new cable cars. Wire rope systems cost one-tenth as much and had lower friction losses than line shafts, because of these advantages, wire rope systems were used to transmit power for a distance of a few miles or kilometers. In America wire rope was manufactured by John A. Roebling, forming the basis for his success in suspension bridge building, Roebling introduced a number of innovations in the design and manufacture of wire rope. Steel wires for wire ropes are made of non-alloy carbon steel with a carbon content of 0.4 to 0. 95%. The very high strength of the wires enables wire ropes to support large tensile forces
In woodworking and construction, a nail is a pin-shaped object of metal which is used as a fastener, as a peg to hang something, or sometimes as a decoration. Generally nails have a point on one end and a flattened head on the other. Nails are made in a variety of forms for specialized purposes. The most common is a wire nail, other types of nails include pins, tacks and cleats. Nails are typically driven into the workpiece by a hammer, a nail gun. A nail holds materials together by friction in the axial direction, the point of the nail is sometimes bent over or clinched after driving to prevent pulling out. The history of the nail is divided roughly into three periods, Hand-wrought nail Cut nail Wire nail To make a wrought-iron nail, iron ore is heated with carbon. To make a nail, a blacksmith heats the rod in a forge, the smith cuts off the taper, and inserts it into a nail heading tool with a square hole. The top of the taper is hammered downward to form a head, Nails date back at least to Ancient Egypt — bronze nails found in Egypt have been dated 3400 BC.
The Romans made extensive use of nails, the Roman army, for example, left behind seven tons of nails when it evacuated the fortress of Inchtuthil in Perthshire in the United Kingdom in 86 or 87 CE. The term penny, as it refers to nails, probably originated in medieval England to describe the price of a hundred nails, Nails themselves were sufficiently valuable and standardized to be used as an informal medium of exchange. Until around 1800 artisans known as nailers or nailors made nails by hand – note the surname Naylor, at the time of the American Revolution, England was the largest manufacturer of nails in the world. Nails were expensive and difficult to obtain in the American colonies, families often had small nail-manufacturing setups in their homes, during bad weather and at night, the entire family might work at making nails for their own use and for barter. Thomas Jefferson wrote in a letter, In our private pursuits it is an advantage that every honest employment is deemed honorable. I am myself a nail maker, the production of wrought-iron nails continued well into the 19th century, but ultimately was reduced to nails for purposes for which the softer cut nails were unsuitable, including horseshoe nails.
Originally, nails were handmade, and the process was slow, nails were relatively few. This naturally produced a desire to create machines to speed up and these nails were known as cut nails or square nails because of their roughly rectangular cross section. Cut nails were one of the important factors in the increase in balloon framing beginning in the 1830s, though still used for historical renovations, and for heavy-duty applications, such as attaching boards to masonry walls, cut nails are much less common today than wire nails
Steel is an alloy of iron and other elements, primarily carbon, that is widely used in construction and other applications because of its high tensile strength and low cost. Steels base metal is iron, which is able to take on two forms, body centered cubic and face centered cubic, depending on its temperature. It is the interaction of those allotropes with the elements, primarily carbon. In the body-centred cubic arrangement, there is an atom in the centre of each cube. Carbon, other elements, and inclusions within iron act as hardening agents that prevent the movement of dislocations that otherwise occur in the lattices of iron atoms. The carbon in steel alloys may contribute up to 2. 1% of its weight. Steels strength compared to pure iron is possible at the expense of irons ductility. With the invention of the Bessemer process in the mid-19th century and this was followed by Siemens-Martin process and Gilchrist-Thomas process that refined the quality of steel. With their introductions, mild steel replaced wrought iron, further refinements in the process, such as basic oxygen steelmaking, largely replaced earlier methods by further lowering the cost of production and increasing the quality of the product.
Today, steel is one of the most common materials in the world and it is a major component in buildings, tools, automobiles, machines and weapons. Modern steel is generally identified by various grades defined by assorted standards organizations, the noun steel originates from the Proto-Germanic adjective stakhlijan, which is related to stakhla. The carbon content of steel is between 0. 002% and 2. 1% by weight for plain iron–carbon alloys and these values vary depending on alloying elements such as manganese, nickel, tungsten, carbon and so on. Basically, steel is an alloy that does not undergo eutectic reaction. In contrast, cast iron does undergo eutectic reaction, too little carbon content leaves iron quite soft and weak. Carbon contents higher than those of steel make an alloy, commonly called pig iron, while iron alloyed with carbon is called carbon steel, alloy steel is steel to which other alloying elements have been intentionally added to modify the characteristics of steel. Common alloying elements include, nickel, molybdenum, titanium, tungsten and niobium.
Additional elements are important in steel, sulfur and traces of oxygen and copper. Alloys with a higher than 2. 1% carbon content, depending on other element content, cast iron is not malleable even when hot, but it can be formed by casting as it has a lower melting point than steel and good castability properties
A galvanic anode is the main component of a galvanic cathodic protection system used to protect buried or submerged metal structures from corrosion. They are made from an alloy with a more active voltage than the metal of the structure. The difference in potential between the two means that the galvanic anode corrodes, so that the anode material is consumed in preference to the structure. The loss of the material gives rise to the alternative name of sacrificial anode. In brief, corrosion is a reaction occurring by an electrochemical mechanism. During corrosion there are two reactions, where electrons leave the metal and reduction, where the electrons are used to water or oxygen to hydroxides. Electric current will flow from the areas into the electrolyte as the metal corrodes. Conversely, as the current flows from the electrolyte to the cathodic areas the rate of corrosion is reduced. As the metal continues to corrode, the potentials on the surface of the metal will change. As a result, in metals, a general covering of rust is formed over the whole surface.
This is rather a view of the corrosion process, because it can occur in several different forms. This effectively stops the oxidation reactions on the surface by transferring them to the galvanic anode. There are three main metals used as anodes, magnesium and zinc. They are all available as blocks, plates or extruded ribbon, each material has advantages and disadvantages. Magnesium has the most negative electropotential of the three and is suitable for areas where the electrolyte resistivity is higher. This is usually on-shore pipelines and other buried structures, although it is used on boats in fresh water. Where this is a possibility, zinc anodes may be used and aluminium are generally used in salt water, where the resistivity is generally lower. Zinc is considered a material, but is not suitable for use at higher temperatures, as it tends to passivate, if this happens, current may cease to flow
Pipe (fluid conveyance)
It can be used for structural applications, hollow pipe is far stiffer per unit weight than solid members. In common usage the words pipe and tube are usually interchangeable, but in industry and engineering, depending on the applicable standard to which it is manufactured, pipe is generally specified by a nominal diameter with a constant outside diameter and a schedule that defines the thickness. Tube is most often specified by the OD and wall thickness, Pipe is generally manufactured to one of several international and national industrial standards. While similar standards exist for specific industry application tubing, tube is made to custom sizes. Many industrial and government standards exist for the production of pipe, the term tube is commonly applied to non-cylindrical sections, i. e. square or rectangular tubing. In general, pipe is the common term in most of the world. Both pipe and tube imply a level of rigidity and permanence, Pipe assemblies are almost always constructed with the use of fittings such as elbows, and so on, while tube may be formed or bent into custom configurations.
For materials that are inflexible, cannot be formed, or where construction is governed by codes or standards, pipe is used for many purposes that do not involve conveying fluid. Handrails and support structures are constructed from structural pipe. There are three processes for metallic pipe manufacture, centrifugal casting of hot alloyed metal is one of the most prominent process. Ductile iron pipes are manufactured in such a fashion. Seamless pipe is formed by drawing a solid billet over a rod to create the hollow shell. As the manufacturing process does not include any welding, seamless pipes are perceived to be stronger, seamless pipe was regarded as withstanding pressure better than other types, and was often more available than welded pipe. Advances since the 1970s in materials, process control, and non-destructive testing, Welded pipe is formed by rolling plate and welding the seam. The weld flash can be removed from both inner and outer surfaces using a scarfing blade, the weld zone can be heat-treated to make the seam less visible.
Welded pipe often have tighter dimensional tolerances than the seamless type, there are a number of processes that may be used to produce ERW pipes. Each of these leads to coalescence or merging of steel components into pipes. Electric current is passed through the surfaces that have to be welded together, as the components being welded together resist the electric current, ERW pipes are manufactured from the longitudinal welding of steel
A vehicle frame is the main supporting structure of a motor vehicle to which all other components are attached, comparable to the skeleton of an organism. Until the 1930s, virtually every car had a structural frame and this construction design is known as body-on-frame. Over time, nearly all cars have migrated to unibody construction, meaning their chassis. Nearly all trucks and most pickups continue to use a frame as their chassis. The main functions of a frame in motor vehicles are, To support the mechanical components and body To deal with static and dynamic loads. These include, Weight of the body and cargo loads and torsional twisting transmitted by going over uneven surfaces. Transverse lateral forces caused by conditions, side wind. Torque from the engine and transmission, longitudinal tensile forces from starting and acceleration, as well as compression from braking. In the case of a chassis, the frame is made up of structural elements called the rails or beams. These are ordinarily made of steel sections, made by folding, rolling or pressing steel plate.
There are three designs for these. If the material is folded twice, an open-ended cross-section, either C-shaped or hat-shaped results and it is made by taking a flat piece of steel and rolling both sides over to form a c-shaped beam running the length of the vehicle. Hat Hat frames resemble a U and may be either right-side-up or inverted with the area facing down. Not commonly used due to weakness and a propensity to rust, however they can be found on 1936–1954 Chevrolet cars, abandoned for a while, the hat frame gained popularity again when companies started welding it to the bottom of unibody cars, in effect creating a boxed frame. Boxed Originally, boxed frames were made by welding two matching C-rails together to form a rectangular tube, modern techniques, use a process similar to making C-rails in that a piece of steel is bent into four sides and welded where both ends meet. While appearing at first glance as a form made of metal. The first issue addressed is beam height, or the height of the side of a frame.
The taller the frame, the better it is able to resist vertical flex when force is applied to the top of the frame and this is the reason semi-trucks have taller frame rails than other vehicles instead of just being thicker
A nut is a type of fastener with a threaded hole. Nuts are almost always used in conjunction with a bolt to fasten two or more parts together. The two partners are kept together by a combination of their threads friction, a stretching of the bolt. Square nuts, as well as heads, were the first shape made and used to be the most common largely because they were much easier to manufacture. It takes only one sixth of a rotation to obtain the side of the hexagon. However, polygons with more than six sides do not give the requisite grip, other specialized shapes exist for certain needs, such as wingnuts for finger adjustment and captive nuts for inaccessible areas. A wide variety of nuts exists, from household hardware versions to specialized industry-specific designs that are engineered to meet various technical standards. Fasteners used in automotive and industrial applications usually need to be tightened to a specific setting, using a torque wrench.9 bolt without stripping. Likewise, an SAE class 5 nut can support the load of an SAE class 5 bolt.
For example, wrench sizes of fastener used in Japanese built cars comply with JIS automotive standard, in normal use, a nut-and-bolt joint holds together because the bolt is under a constant tensile stress called the preload. If the joint is subjected to vibration, the increases and decreases with each cycle of movement. If the minimum preload during the cycle is not enough to hold the nut firmly in contact with the bolt. Specialized locking nuts exist to prevent this problem, but sometimes it is sufficient to add a second nut, for this technique to be reliable, each nut must be tightened to the correct torque. The inner nut is tightened to about a quarter to a half of the torque of the outer nut and it is held in place by a wrench while the outer nut is tightened on top using the full torque. This arrangement causes the two nuts to push on other, creating a tensile stress in the short section of the bolt that lies between them. Even when the joint is vibrated, the stress between the two nuts remains constant, thus holding the nut threads in constant contact with the bolt threads.
When the joint is assembled correctly, the outer nut bears the tension of the joint. The inner nut functions merely to add an additional force to the outer nut and does not need to be as strong
Paint is any liquid, liquefiable, or mastic composition that, after application to a substrate in a thin layer, converts to a solid film. It is most commonly used to protect, color, or provide texture to objects, Paint can be made or purchased in many colors—and in many different types, such as watercolor, etc. Paint is typically stored and applied as a liquid, in 2001 and 2004, South African archeologists reported finds in Blombos Cave of a 100, 000-year-old human-made ochre-based mixture that could have been used like paint. Further excavation in the cave resulted in the 2011 report of a complete toolkit for grinding pigments. Cave paintings drawn with red or yellow ochre, manganese oxide, ancient colored walls at Dendera, which were exposed for years to the elements, still possess their brilliant color, as vivid as when they were painted about 2,000 years ago. The Egyptians mixed their colors with a substance, and applied them separately from each other without any blending or mixture. They appear to have used six colors, black, red and they first covered the area entirely with white, traced the design in black, leaving out the lights of the ground color.
They used minium for red, and generally of a dark tinge, pliny mentions some painted ceilings in his day in the town of Ardea, which had been done prior to the foundation of Rome. He expresses great surprise and admiration at their freshness, after the lapse of so many centuries, Paint was made with the yolk of eggs and therefore, the substance would harden and adhere to the surface it was applied to. Pigment was made from plants and different soils, Most paints used either oil or water as a base. The process was done by hand by the painters and exposed them to lead poisoning due to the white-lead powder, in 1718, Marshall Smith invented a Machine or Engine for the Grinding of Colours in England. It is not known precisely how it operated, but it was a device that increased the efficiency of pigment grinding dramatically. By the proper onset of the Industrial Revolution, paint was being ground in steam-powered mills, interior house painting increasingly became the norm as the 19th century progressed, both for decorative reasons and because the paint was effective in preventing the walls rotting from damp.
Linseed oil was used as an inexpensive binder. In 1866, Sherwin-Williams in the United States opened as a large paint-maker and it was not until the stimulus of World War II created a shortage of linseed oil in the supply market that artificial resins, or alkyds, were invented. Cheap and easy to make, they held the color well. The vehicle is composed of the binder, or, if it is necessary to thin the binder with a diluent like solvent or water, it is the combination of binder + diluent. In this case, once the paint has dried or cured very nearly all of the diluent has evaporated, thus, an important quantity in coatings formulation is the vehicle solids, sometimes called the resin solids of the formula
A screw is a type of fastener, sometimes similar to a bolt, typically made of metal, and characterized by a helical ridge, known as a male thread or just thread. A screw is an inclined plane wrapped around a nail, some screw threads are designed to mate with a complementary thread, known as a female thread, often in the form of a nut or an object that has the internal thread formed into it. Other screw threads are designed to cut a groove in a softer material as the screw is inserted. The most common uses of screws are to hold objects together, a screw will usually have a head on one end that contains a specially formed shape that allows it to be turned, or driven, with a tool. Common tools for driving screws include screwdrivers and wrenches, the head is usually larger than the body of the screw, which keeps the screw from being driven deeper than the length of the screw and to provide a bearing surface. The cylindrical portion of the screw from the underside of the head to the tip is known as the shank, the distance between each thread is called the pitch.
Another rule is this, curl the fingers of right hand around the screw with your thumb pointing is the direction you want the screw to go. If the screw is right-handed and you turn the screw in the direction of your fingers the screw will move in the direction of your thumb, Screws with left-hand threads are used in exceptional cases. For example, when the screw will be subject to counterclockwise torque, the right side pedal of a bicycle has a left-hand thread. More generally, screw may mean any helical device, such as a clamp, a micrometer, there is no universally accepted distinction between a screw and a bolt. So, as a rule, when buying a packet of screws you would not expect nuts to be included. Part of the confusion over this is due to regional or dialectical differences. An externally threaded fastener which is prevented from being turned during assembly, an externally threaded fastener that has thread form which prohibits assembly with a nut having a straight thread of multiple pitch length is a screw.
This distinction is consistent with ASME B18.2.1 and some dictionary definitions for screw, some of these issues are discussed below, ASME standards specify a variety of Machine Screws in diameters ranging up to 0.75 in. These fasteners are used with nuts but often driven into tapped holes. They might be considered a screw or a bolt based on the Machinerys Handbook distinction, ASME standard B18.2. 1-1996 specifies Hex Cap Screws that range in size from 0. 25–3 in in diameter. These fasteners are very similar to hex bolts and they differ mostly in that they are manufactured to tighter tolerances than the corresponding bolts. Machinerys Handbook refers parenthetically to these fasteners as Finished Hex Bolts, in 1991 responding to an influx of counterfeit fasteners Congress passed PL 101-592 Fastener Quality Act This resulted in the rewriting of specifications by the ASME B18 committee
Plumbing is any system that conveys fluids for a wide range of applications. Plumbing uses pipes, plumbing fixtures, tanks and cooling, waste removal, and potable water delivery are among the most common uses for plumbing, but it is not limited to these applications. The word derives from the Latin for lead, plumbum, as the first effective pipes used in the Roman era were lead pipes, in the developed world, plumbing infrastructure is critical to public health and sanitation. Boilermakers and pipefitters are not plumbers, although they work with piping as part of their trade, standardized earthen plumbing pipes with broad flanges making use of asphalt for preventing leakages appeared in the urban settlements of the Indus Valley Civilization by 2700 B. C. The Romans used lead pipe inscriptions to prevent water theft, Plumbing reached its early apex in ancient Rome, which saw the introduction of expansive systems of aqueducts, tile wastewater removal, and widespread use of lead pipes. With the Fall of Rome both water supply and sanitation stagnated—or regressed—for well over 1,000 years, improvement was very slow, with little effective progress made until the growth of modern densely populated cities in the 1800s.
During this period, public authorities began pressing for better waste disposal systems to be installed. Earlier, the disposal system had merely consisted of collecting waste. Eventually the development of separate, underground water and sewage systems eliminated open sewage ditches, most large cities today pipe solid wastes to sewage treatment plants in order to separate and partially purify the water, before emptying into streams or other bodies of water. For potable water use, galvanized iron piping was commonplace in the United States from the late 1800s until around 1960, after that period, copper piping took over, first soft copper with flared fittings, with rigid copper tubing utilizing soldered fittings. The use of lead for potable water declined sharply after World War II because of increased awareness of the dangers of lead poisoning, at this time, copper piping was introduced as a better and safer alternative to lead pipes. e. Heating and cooling systems utilizing water to transport thermal energy, as in district heating systems, a water pipe is a pipe or tube, frequently made of plastic or metal, that carries pressurized and treated fresh water to a building, as well as inside the building.
For many centuries, lead was the material for water pipes. This was a source of lead-related health problems in the years before the hazards of ingesting lead were fully understood, among these were stillbirths. Lead water pipes were still used in the early 20th century. In addition, lead-tin alloy solder was commonly used to join copper pipes, despite the Romans common use of lead pipes, their aqueducts rarely poisoned people. Unlike other parts of the world where lead pipes cause poisoning, what often causes confusion is the large amount of evidence of widespread lead poisoning, particularly amongst those who would have had easy access to piped water. This was a result of lead being used in cookware and as an additive to processed food and drink
Paris is the capital and most populous city of France. It has an area of 105 square kilometres and a population of 2,229,621 in 2013 within its administrative limits, the agglomeration has grown well beyond the citys administrative limits. By the 17th century, Paris was one of Europes major centres of finance, fashion and the arts, and it retains that position still today. The aire urbaine de Paris, a measure of area, spans most of the Île-de-France region and has a population of 12,405,426. It is therefore the second largest metropolitan area in the European Union after London, the Metropole of Grand Paris was created in 2016, combining the commune and its nearest suburbs into a single area for economic and environmental co-operation. Grand Paris covers 814 square kilometres and has a population of 7 million persons, the Paris Region had a GDP of €624 billion in 2012, accounting for 30.0 percent of the GDP of France and ranking it as one of the wealthiest regions in Europe. The city is a rail and air-transport hub served by two international airports, Paris-Charles de Gaulle and Paris-Orly.
Opened in 1900, the subway system, the Paris Métro. It is the second busiest metro system in Europe after Moscow Metro, Paris Gare du Nord is the busiest railway station in the world outside of Japan, with 262 millions passengers in 2015. In 2015, Paris received 22.2 million visitors, making it one of the top tourist destinations. The association football club Paris Saint-Germain and the rugby union club Stade Français are based in Paris, the 80, 000-seat Stade de France, built for the 1998 FIFA World Cup, is located just north of Paris in the neighbouring commune of Saint-Denis. Paris hosts the annual French Open Grand Slam tennis tournament on the red clay of Roland Garros, Paris hosted the 1900 and 1924 Summer Olympics and is bidding to host the 2024 Summer Olympics. The name Paris is derived from its inhabitants, the Celtic Parisii tribe. Thus, though written the same, the name is not related to the Paris of Greek mythology. In the 1860s, the boulevards and streets of Paris were illuminated by 56,000 gas lamps, since the late 19th century, Paris has been known as Panam in French slang.
Inhabitants are known in English as Parisians and in French as Parisiens and they are pejoratively called Parigots. The Parisii, a sub-tribe of the Celtic Senones, inhabited the Paris area from around the middle of the 3rd century BC. One of the areas major north-south trade routes crossed the Seine on the île de la Cité, this place of land and water trade routes gradually became a town