The Aerial Lift Bridge (earlier known as the Aerial Bridge or Aerial Ferry Bridge) is a major landmark in the port city of Duluth, Minnesota. The span began life as an extremely rare transporter bridge — the first of just two such bridges ever constructed in theUnited States.[2] Originally built in 1905, the bridge was upgraded in 1929–30 to a vertical lift bridge, which is rather uncommon, (although there are six such bridges along Ontario's Welland Canal), and continues to operate today. The bridge was added to theNational Register of Historic Places on May 22, 1973. A maritime museum maintained by the United States Army Corps of Engineersexists near the site of the bridge.
Bridge history
Aerial gondola, circa 1908
The bridge spans the Duluth Ship Canal, which was put through the thin but long sand spit named Minnesota Point (commonly referred to as Park Point by locals) in 1870–71. The natural mouth of the Saint Louis River is about seven miles (11 km) farther southeast, and is split between Minnesota and Wisconsin. Creating this gap in the tiny peninsula meant that residents who lived on the new island needed to have a way to get across. Several different transportation methods were tried, though they were complicated by the weather. Ferries could work in the summer, but ice caused problems in colder months. A swinging footbridge was used, but was considered rather rickety and unsafe.
In 1892, a contest was held to find a solution. The winning design came from John Low Waddell, who drew up plans for a high-rise vertical lift bridge. The city of Duluth was eager to build the bridge, which would have been about 130 feet (40 m) wide. However, the War Department objected to the design, and the project was canceled before it could be built. Waddell's design went on to be built in Chicago, Illinois as the slightly larger South Halsted Street Bridge (removed in 1932).[3][4][5]
New plans were later drawn up for a structure that would ferry people from one side to the other. This type of span, which is known variously as an aerial transfer, ferry, or transporter bridge, was first demonstrated in Bilbao's Vizcaya Bridge in 1893 and one in France in 1898. Duluth's bridge was inspired by the one in France, though the actual construction is quite different. The architect was a city engineer, Thomas McGilvray.[1]
The Aerial Lift Bridge dominates the Canal Park skyline. (2005)
When it was completed in 1905, the Aerial Bridge's gondola had a capacity of 60 short tons (54tonne) and could carry 350 people plus wagons, streetcars or automobiles. A trip across the canal took about one minute, and the ferry car moved across once every five minutes during busy times of the day.[6] A growing population on Minnesota Point, a greater demand for cars, and an increase in tourism soon meant that the bridge's capacity was being stretched to the limit.
A remodeling was planned that would remove the gondola and incorporate a lifting platform into the structure. The firm finally commissioned with designing the new bridge was the descendant of Waddell's company. The new design, which closely resembles the 1892 concept, is attributed to C.A.P. Turner. Reconstruction began in 1929.[1] In order to ensure that tall ships could still pass under the bridge, the top span had to be raised to accommodate the new deck when raised. The support columns on either side were also modified so that they could hold new counterweights to balance the weight of the lifting portion. The new bridge first lifted for a vessel on March 29, 1930.[6]
The bridge can be raised to its full height of 135 feet in about a minute, and is raised approximately five thousand times per year.[7] The span is about 390 feet (120 meters). As ships pass, there is a customary horn-blowing sequence that is copied back. The bridge's "horn" is actually made up of two Westinghouse Airbrake locomotive horns.[8] Long-short-long-short means to raise the bridge, and Long-short-short is a friendly salute.
A "Hello, World!" program is a computer program that outputs or displays "Hello, World!" to the user. Being a very simple program in most programming languages, it is often used to illustrate the basic syntax of a programming language for a working program.
Purpose
A "Hello, world!" program is often used to introduce beginning programmers to a programming language. In general, it is simple enough to be understood easily, especially with the guidance of a teacher or a written guide.
In addition, "Hello world!" can be a useful sanity test to make sure that a language's compiler, development environment, and run-time environment are correctly installed.[original research?] Configuring a complete programming toolchain from scratch to the point where even trivial programs can be compiled and run can involve substantial amounts of work. For this reason, a simple program is used first when testing a new tool chain.[citation needed]
A "Hello world!" program running on Sony's PlayStation Portable as a proof of concept.
"Hello world!" is also used by computer hackers as a proof of concept that arbitrary code can be executed through an exploit where the system designers did not intend code to be executed—for example, on Sony's PlayStation Portable. This is the first step in using homemade content ("home brew") on such a device.
"Hello, world." was used as their first Tweet in 2016 by the previously secretive GCHQ UK communications interception agency.[1][2]
History
While small test programs existed since the development of programmable computers, the tradition of using the phrase "Hello world!" as a test message was influenced by an example program in the seminal book The C Programming Language[citation needed]. The example program from that book prints "hello, world" (without capital letters or exclamation mark), and was inherited[citation needed] from a 1974Bell Laboratories internal memorandum by Brian Kernighan, Programming in C: A Tutorial,[3] which contains the first known version:
The C version was adapted[citation needed] from Kernighan's 1972 A Tutorial Introduction to the Language B,[4] where the first known version of the program is found in an example used to illustrate external variables:
main(){
extrn a,b,c;
putchar(a); putchar(b); putchar(c); putchar('!*n');
}
a 'hell';
b 'o, w';
c 'orld';
The program prints hello, world! on the terminal, including a newline character. The phrase is divided into multiple variables because in B, a character constant is limited to fourASCII characters. The previous example in the tutorial printed hi! on the terminal, and the phrase hello, world! was introduced as a slightly longer greeting that required several character constants for its expression.
It is also claimed that[by whom?]hello, world originated instead with BCPL (1967).[5][unreliable source?]This claim is supported by the archived notes of the inventors of BCPL, Prof. Brian Kernighan at Princeton and Martin Richards at Cambridge.[citation needed]
For modern languages, hello world programs vary in sophistication. For example, the Go programming language introduced a multilingual program,[6]Sun demonstrated a Javahello world based on scalable vector graphics,[7] and the XL programming language features a spinning Earth hello world using 3D graphics.[8] While some languages such asPerl, Python or Ruby may need only a single statement to print "hello world", a low-level assembly language may require dozens of commands. Mark Guzdial and Elliot Soloway have suggested that the "hello world" test message may be outdated now that graphics and sound can be manipulated as easily as text.[9]
Variations
There are many variations on the punctuation and casing of the phrase. Variations include the presence or absence of the comma and exclamation mark, and the capitalization of the 'H', both the 'H' and the 'W', or neither. Some languages are forced to implement different forms, such as "HELLO WORLD!", on systems that support only capital letters, while many "hello world" programs in esoteric languages print out a slightly modified string. For example, the first non-trivial Malbolge program printed "HEllO WORld", this having been determined to be good enough.[citation needed]
There are variations in spirit, as well. Functional programming languages, like Lisp, ML and Haskell, tend to substitute a factorial program for Hello World, as functional programming emphasizes recursive techniques, whereas the original examples emphasize I/O, which violates the spirit of pure functional programming by producing side effects. Languages otherwise capable of Hello World (Assembly, C, VHDL) may also be used in embedded systems, where text output is either difficult (requiring additional components or communication with another computer) or nonexistent. For devices such as microcontrollers, field-programmable gate arrays, and CPLD's, "Hello, World" may thus be substituted with a blinking LED, which demonstrates timing and interaction between components.[10][11][12][13][14]
The Debian and UbuntuLinux distributions provide the "hello world" program through the apt packaging system; this allows users to simply type "apt-get install hello" for the program to be installed, along with any software dependencies. While of itself useless, it serves as a sanity check and a simple example to newcomers of how to install a package. It is significantly more useful for developers, however, as it provides an example of how to create a .deb package, either traditionally or using debhelper, and the version of hello used, GNU Hello, serves as an example of how to write a GNU program.
