Little Willie was a prototype in the development of the British Mark I tank. Constructed in the autumn of 1915 at the behest of the Landship Committee, it was the first completed tank prototype in history. Little Willie is the oldest surviving individual tank, is preserved as one of the most famous pieces in the collection of The Tank Museum, England. Work on Little Willie's predecessor was begun in July 1915 by the Landship Committee to meet The United Kingdom's requirement in World War I for an armoured combat vehicle able to cross an 8-foot trench. After several other projects where single and triple tracks had failed, on 22 July William Ashbee Tritton, director of the agricultural machinery company William Foster & Company of Lincoln, was given the contract to develop a "Tritton Machine" with two tracks, it had to make use of the track assemblies – lengthened tracks and suspension elements – purchased as built units from the Bullock Creeping Grip Tractor Company in Chicago. On 11 August actual construction began.

On 9 September the Number 1 Lincoln Machine, as the prototype was known, made its first test run in the yard of the Wellington Foundry. It soon became clear that the track profiles were so flat that ground resistance during a turn was excessive. To solve this, the suspension was changed; the next problem showed up: when crossing a trench the track sagged and would not fit the wheels again and jammed. The tracks were not up to carrying the weight of the vehicle. Tritton and Lieutenant Walter Gordon Wilson tried several types of alternative track design, including balatá belting and flat wire ropes. Tritton, on 22 September, devised a robust but outwardly crude system using pressed steel plates riveted to cast links and incorporated guides to engage on the inside of the track frame; the track frames as a whole were connected to the main body by large spindles. This system was unsprung, as the tracks were held in place, able to move in only one plane; this was a successful design and was used on all First World War British tanks up to the Mark VIII, although it limited speed.

The vehicle's 13 litre 105 bhp Daimler-Knight engine, gravity fed by two petrol tanks, was at the back, leaving just enough room beneath the turret. The prototype was fitted with a non-rotatable dummy turret mounting a machine gun; the main gun would have had a large ammunition store with 800 rounds. Stern suggested to Tritton that the gun could be made to slide forward on rails, giving a better field of fire, but in the event the turret idea was abandoned and the aperture for the crew plated over. In the front of the vehicle two men sat on a narrow bench. Overall length of the final version with the lengthened tracks and rear steering wheels in place was 8.08 m. The length of the main unit without the rear steering wheels installed is 5.87 m. Most mechanical components, including the radiator, had been adapted from those of the Foster-Daimler heavy artillery tractor; as at least four men would have been required to operate the armament, the crew could not have been smaller than six. The maximum speed was indicated by Tritton as being no more than two miles per hour.

The vehicle used no real armour steel, just boiler plate. Wilson was unhappy with the basic concept of the Number 1 Lincoln Machine, on 17 August suggested to Tritton the idea of using tracks that ran all around the vehicle. With d'Eyncourt's approval construction of an improved prototype began on 17 September. For this second prototype, a rhomboid track frame was fitted, taking the tracks up and over the top of the vehicle; the rear steering wheels were retained in an improved form, but the idea of a turret was abandoned and the main armament placed in side sponsons. Number 1 Lincoln Machine was rebuilt with an extended track up to 6 December 1915, but to test the new tracks in Burton Park, near Lincoln; the first was renamed Little Willie, the scabrous name commonly used by the British yellow press to mock the German Imperial Crown Prince Wilhelm. That same year the cartoonist William Kerridge Haselden had made a popular comic anti-German propaganda movie: The Adventures of Big and Little Willie.

Although Little Willie was demonstrated alongside Mother in January 1916, it was by peripheral to the development of British tanks. Though it never saw combat, Little Willie was a major step forward in military technology, being the first tank prototype to be finished. During the remainder of World War I, some tank crews continued to informally refer to their vehicles as "Willies" or "buses". In 1922 the Royal Tank Regiment adopted. Little Willie was preserved for posterity after the war, having been saved from being scrapped in 1940, is today displayed at The Tank Museum at Bovington, it is an empty hull, without an engine, but still with some internal fittings. The rear steering wheels are not fitted and there is damage to the hull plating around the right–hand vision slit caused by an attempt at some point to tow the vehicle by passing a cable thro

A natural monopoly is a monopoly in an industry in which high infrastructural costs and other barriers to entry relative to the size of the market give the largest supplier in an industry the first supplier in a market, an overwhelming advantage over potential competitors. This occurs in industries where capital costs predominate, creating economies of scale that are large in relation to the size of the market. Natural monopolies were recognized as potential sources of market failure early as the 19th century. Two different types of cost are important in microeconomics: marginal cost, fixed cost; the marginal cost is the cost to the company of serving one more customer. In an industry where a natural monopoly does not exist, the vast majority of industries, the marginal cost decreases with economies of scale increases as the company has growing pains. Along with this, the average cost of its products increases. A natural monopoly has a different cost structure. A natural monopoly has a high fixed cost for a product that does not depend on output, but its marginal cost of producing one more good is constant, small.

All industries have costs associated with entering them. A large portion of these costs is required for investment. Larger industries, like utilities, require enormous initial investment; this barrier to entry reduces the number of possible entrants into the industry regardless of the earning of the corporations within. Natural monopolies arise where the largest supplier in an industry the first supplier in a market, has an overwhelming cost advantage over other actual or potential competitors; the fixed cost of constructing a competing transmission network is so high, the marginal cost of transmission for the incumbent so low, that it bars potential competitors from the monopolist's market, acting as a nearly insurmountable barrier to entry into the market place. A firm with high fixed costs requires a large number of customers in order to have a meaningful return on investment; this is. Since each firm has large initial costs, as the firm gains market share and increases its output the fixed cost is divided among a larger number of customers.

Therefore, in industries with large initial investment requirements, average total cost declines as output increases over a much larger range of output levels. Companies that take advantage of economies of scale run into problems of bureaucracy. If that ideal size is large enough to supply the whole market that market is a natural monopoly. Once a natural monopoly has been established because of the large initial cost and that, according to the rule of economies of scale, the larger corporation has lower average cost and therefore a huge advantage. With this knowledge, no firms attempt to enter the industry and an oligopoly or monopoly develops. William Baumol provided the current formal definition of a natural monopoly where "n industry in which multi-firm production is more costly than production by a monopoly", he linked the definition to the mathematical concept of subadditivity. Baumol noted that for a firm producing a single product, scale economies were a sufficient but not a necessary condition to prove subadditivity.

The original concept of natural monopoly is attributed to John Stuart Mill, who believed that prices would reflect the costs of production in absence of an artificial or natural monopoly. In Principles of Political Economy Mill criticised Smith's neglect of an area that could explain wage disparity. Taking up the examples of professionals such as jewellers and lawyers, he said, The superiority of reward is not here the consequence of competition, but of its absence: not a compensation for disadvantages inherent in the employment, but an extra advantage. If unskilled labourers had it in their power to compete with skilled, by taking the trouble of learning the trade, the difference of wages might not exceed what would compensate them for that trouble, at the ordinary rate at which labour is remunerated, but the fact that a course of instruction is required, of a low degree of costliness, or that the labourer must be maintained for a considerable time from other sources, suffices everywhere to exclude the great body of the labouring people from the possibility of any such competition.

So Mill's initial use of the term concerned natural abilities, in contrast to the common contemporary usage, which refers to market failure in a particular type of industry, such as rail, post or electricity. Mill's development of the idea is. All the natural monopolies (meaning thereby those which are created by circumstances, not by la

The Yingwuzhou Yangtze River Bridge is a bridge carrying the southern section of the Second Ring Road over the Yangtze River in Wuhan, Hubei Province, China. It is one of the longest suspension bridges in the world with two consecutive 850 m spans; the bridge cost 3.08 billion yuan to build and opened on December 28, 2014. Yingwuzhou means "parrot island," a famous island, mentioned many times in Tang dynasty poems, but has now been part of Hanyang due to the redirection of the river. Bridges and tunnels across the Yangtze River List of longest suspension bridge spans List of largest bridges in China