First produced in 1896 as one of the first commercially successful and practical semi-automatic pistols, Spanish gunmakers in the late 1920s introduced " select fire " copies of the C96 with detachable magazines, and in the early 1930s Mauser engineers introduced the model 711 and 712 Schnellfeuer variants, which included a fire selector mechanism allowing fully automatic fire at a rate of 1000 rounds / minute.

A working solar cell, of low efficiency, was constructed by Charles Fritts in 1883 using a metal plate coated with selenium and a thin layer of gold ; the device became commercially useful in photographic light meters in the 1930s.

The operational principles of the ratio pyrometers were developed in the 1920s and 1930s, and they were commercially available in 1939.

Later, in the 1920s and 1930s, factories were built that commercially extracted pectin from dried apple pomace and later citrus-peel in regions that produced apple juice in both the USA and in Europe.

These diesel-powered trains featured a then-impressive top speed of 120 km / h as well as a high level of comfort, and they proved themselves DSB's most commercially successful initiative of the 1930s.

In the early and mid-1930s, Laemmle's son, Carl Laemmle, Jr., produced a series of expensive and commercially unsuccessful films for the studio, although there were occasional successes such as 1932's Back Street, 1936's Show Boat, and Universal's famous collection of 1930s horror classics.

Research by members of the college into animal genetics in the 1930s led to the development of new breeds of sheep, the Drysdale and the Perendale, which became commercially significant after World War II.

In the 1920s and 1930s, evaporated milk began to be widely commercially available at low prices, and several clinical studies from that time period suggested that babies fed evaporated milk formula thrive as well as breastfed babies.

Harry DeArmond ( January 28, 1906-October 12, 1999 ) invented the first commercially available attachable guitar pickup in the mid 1930s.

From the 1880s tobacco was grown commercially but petered out in the late 1930s.

The modern autopen called the Robot Pen was developed in the 1930s and became commercially available in 1937 ( used as a storage unit device, similar in principle to how vinyl records store information ) to record a signers signature.

Cyanogen iodide was considered one of the impurities in commercially sold iodine before the 1930s.

Prontosil, the first commercially available antibacterial antibiotic ( with a relatively broad effect against Gram-positive cocci but not against enterobacteria ), was developed in the 1930s by a research team at the Bayer Laboratories of the IG Farben conglomerate in Germany.

Producing a commercially viable abrasive waterjet nozzle came next, and an engineering research team at Flow Industries built on their high-pressure pump research, as well as Tirrell ’ s original nozzle design from the 1930s and Schwacha ’ s research in high-pressure waterjet cutting from the 1950s, to develop the modern abrasive waterjet nozzle.

It remained a viable organization until the 1930s, in an alliance with the Canadian Labour Party ( see below ).

These streetcar lines were replaced with bus routes in the 1930s and 1940s.

The city's role in trade greatly diminished with the opening of the trans-Iranian railway in the 1930s, as trade routes shifted to the ports in Khuzestan.

By the mid 1930s, more than a dozen different climbing routes had been established on Grand Teton including the northeast ridge in 1931 by Glenn Exum.

The Yosemite Decimal System ( YDS ) of grading routes was initially developed as the Sierra Club grading system in the 1930s to rate hikes and climbs in the Sierra Nevada range.

Abandoned plans dating from the 1920s, to extend the line further southwards, and then northwards in the 1930s, would have incorporated parts of the routes of two further companies.

The first airline alliance started in the 1930s, as Panair do Brasil and parent company Pan American World Airways agreed to exchange routes to Latin America.

In the 1930s, as part of the New Deal the U. S. federal government constructed national parkways designed for recreational driving and to commemorate historic trails and routes.

As the 1930s progressed, SABENA cooperated with Air France and Deutsche Luft Hansa, which also had interests in routes to destinations across Africa.

American blues became known in Britain from the 1930s onwards through a number of routes, including records brought to Britain, particularly by African-American GIs stationed there in the Second World War and Cold War, merchant seamen visiting ports such as London, Liverpool, Newcastle on Tyne and Belfast, and through a trickle of ( illegal ) imports.

In the 1930s, Anne and Charles together explored and charted air routes between continents.

Clarke's design prototypes for the Parkway combined the example of the Pennsylvania Turnpike, a model of efficiency with parallels in the German Autobahn routes of the 1930s, with the Merritt Parkway model that stressed a planted " green belt " for beauty.

In the 1930s, flying boats made it possible to have regular air transport between the U. S. and Europe, opening up new air travel routes to South America, Africa, and Asia.

The motorway, which was first proposed in the 1930s, and originally conceived as two separate routes, was built in stages between 1971 and 1976, with construction beginning at Pole Moor and finishing in Tarbock on the outskirts of Liverpool.

In the 1920s and 1930s, when many countries issued airmail stamps to publicise their new airmail routes, a new branch of stamp collecting started.

By the mid 1930s the Metropolitan Line was suffering from congestion on its main routes from north London caused by the limited capacity of its tracks between Finchley Road and Baker Street stations.

Although it remained financially strong, it did not add routes until the 1930s, when it expanded to Louisiana.

U. S. Route 366 or US 366 was the designation of two child routes of the former U. S. Route 66 in New Mexico and Texas during the late 1920s and 1930s.

German airlines, such as Deutsche Luft Hansa, experimented with mail routes over the North Atlantic in the early 1930s, with seaplanes and dirigibles.

In the late 1930s, domestic air routes already reached all the major cities in Finland, and in 1940 it became possible to fly even to Petsamo in the far north.

In the 1930s, following the integration of train and bus services, it was usual for the summer train service to peak at about a dozen trains each way on all three main routes.

The historic fleet consists of motor buses and trolley buses ranging from ones built in the late 1930s and early 1940s through to ones retired only recently, such as a Breda dual-mode bus, a type which was used for tunnel routes and replaced with hybrid electric buses.

During 1930s he worked as an entertainer on board transatlantic liners on the routes between Europe and North America, which gave him the opportunity to get to know American music genres, especially jazz and swing.

The earliest recorded climbing activity dates from the 1930s, when Harold Goodro put up some routes before shifting to predominantly climbing on the quartzite of Big Cottonwood Canyon and elsewhere.

These steamboat routes operated on the Chesapeake Bay and major rivers until the 1930s before the building of highways and the Harry W. Nice Memorial Bridge on U. S. Highway 301.

Like most trolley companies Public Service converted its routes to bus lines during the 1930s.

In the 1930s catalytic hydrogenation was commercialized, which allowed the conversion of fatty acid esters, typically tallow, to the alcohols.