By the 1920s, each state in the United States had passed public laws that stipulated a certain day to be Arbor Day or Arbor and Bird Day observance.

By the late 1920s Potter and her Hill Top farm manager Tom Storey had made a name for their prize-winning Herdwick flock.

By the 1920s, composers of Tin Pan Alley and Broadway used ballad to signify a slow, sentimental tune or love song, often written in a fairly standardized form ( see below ).

By the late 1920s, New York writers other than Fitz Gerald were starting to use " Big Apple " and were using it outside of a horse-racing context.

By the 1920s, the emerging middle and working classes were powerful enough to elect a reformist president, Arturo Alessandri Palma.

By the 1920s, many newspapers had a comics page on which many strips were collected together.

Additional milieu were provided by Chaosium with the release of Dreamlands, a boxed supplement containing additional rules needed for playing within the Lovecraft Dreamlands, a large map and a scenario booklet, and Cthulhu By Gaslight, another boxed set which moved the action from the 1920s to the 1890s.

By the early 1920s, unit operations became an important aspect of chemical engineering at MIT and other US universities, as well as at Imperial College London.

By the late 1920s, Al Capone and the Mob were inspiring not only fear, but piquing mainstream curiosity about the American underworld.

By the 1920s, the U. S. reached what is still its era of greatest-ever output, producing an average of 800 feature films annually, or 82 % of the global total ( Eyman, 1997 ).

By the 1920s Lewis Fry Richardson's interest in weather prediction led him to propose human computers and numerical analysis to model the weather ; to this day, the most powerful computers on Earth are needed to adequately model its weather using the Navier – Stokes equations.

By the 1920s, the idea of an Israelite conquest of Canaan-the story of the book of Joshua-was not supported by the archaeological record.

By the 1920s, Hearst, was the owner of a chain of newspapers from coast to coast.

By the 1920s, the diatonic harmonica had largely reached its modern form.

By the 1920s however the Senate had lost much of its original influence, and hence no sitting senator had been known to have serious aspirations of becoming prime minister whilst remaining in the Senate.

By the 1920s the number of cars had soared to 60, 000.

By the early 1920s, however, the inherent limitations of this type of engine had rendered it obsolete, with the power output increasingly going into overcoming the air-resistance of the spinning engine itself.

By the 1920s psychoanalysts assumed that homosexuality was pathological and that attempts to treat it were appropriate, although psychoanalytic opinion about changing homosexuality was largely pessimistic.

By the late 1920s the resistance movement against colonial rule had gathered widespread support during the mistreatment of the Samoan people by the New Zealand administration.

By the late 1920s, however, those employing only optical and electronic technologies were being explored.

By the late 1920s, economic performance had stabilised, but the overall situation was disappointing, for Britain had clearly fallen behind the United States and other countries as an industrial power.

By the 1920s, however, this boisterous folksiness had diminished.

By the end of the 1920s Corbusier was already an internationally known architect.

By the 1920s, the British Government were seeking a replacement for their book code systems, which had been shown to be insecure, and which proved to be slow and awkward to use in practice.

" By the 1920s, Birmingham was the 19th largest city in the U. S and held more than 30 % of the population of the state.

By the mid-20th century, it was increasingly clear to historians that the notion of " changeless China " was untenable.

By considering circumscribed spheres, the notion of Delaunay triangulation extends to three and higher dimensions.

By the 1930s, many revisions of the rules developed that were substantially different from Babcock's classical version ( including some that were considered fundamentals in other variants, such as the notion of a standard hand ).

By the twentieth century, the modern notion of science as a special brand of information about the world, practiced by a distinct group and pursued through a unique method, was essentially in place.

By the mid-5th century, land had become concentrated in the hands of a tiny elite, and the notion of all Spartan citizens being " equals " had become a farce.

By 1973, Harvey Milk, who would become the most famous resident of the neighborhood, opened a camera store, Castro Camera, and began political involvement as a gay activist, further contributing to the notion of the Castro as a gay destination.

By creation of a paradox, Plato's Euthydemus dialogue demonstrates the need for the notion of contradiction.

* By showing that the Anschluss was enormously popular in Austria, he helped to discredit the notion of Austria as a victim of Nazi aggression brought unwillingly into the Reich.

By the 7th century CE Indian mathematicians were familiar enough with the notion of infinity as to define it as the quantity whose denominator is zero.

:" By non-phoneticians any mode of pronunciation which is harsh or grating in effect is often supposed to be ' guttural '; with this notion the designation is popularly applied by Englishmen to the German ch, but not to k or g, though technically it belongs equally to them.

By contrast to the notion of civil tolerance, in early modern Europe the subjects were required to attend the state church ; This attitude can be described as territoriality or religious uniformity, and its underlying assumption is brought to a point by a statement of the Anglican theologian Richard Hooker: " There is not any man of the Church of England but the same man is also a member of the commonwealth ; nor any man a member of the commonwealth, which is not also of the Church of England.

By international law, the notion of a country's sovereign airspace corresponds with the maritime definition of territorial waters as being 12 nautical miles ( 22. 2 km ) out from a nation's coastline.

If F is any field, the separable closure F < sup > sep </ sup > of F is the field of all elements in an algebraic closure of F that are separable over F. This is the maximal Galois extension of F. By definition, F is perfect if and only if its separable and algebraic closures coincide ( in particular, the notion of a separable closure is only interesting for imperfect fields ).

By contrast, the more common usage of the term, as found in Catholic social teaching and in European Unioin law and social policy, encompasses the notion that " higher " or more remote levels of social organization have a duty to render assistance to the most immediate, competent level of organization, while respecting the primary jurisdiction of that more immediate level, and, ultimately, the dignity and freedoms of individuals participating in society.

By applying the preceding ideas to the local 1-parameter group of diffeomorphisms defined by a vector field on M, and differentiating with respect to the parameter, a notion of Lie derivative on any associated bundle is obtained.

By his own account, Hörbiger was observing the Moon when he was struck by the notion that the brightness and roughness of its surface was due to ice.

By abstracting the notion of formulae and focusing of their concrete uses, that is distinct occurrences, it allows to provide an abstract syntax for computer science, as loci can be seen as pointers on memory.

By contrast, Theta roles are a syntactic notion about the number, type and placement of obligatory arguments.

By virtue of these changes, the preamble was deleted, the chapters concerning political and economic forms of government were changed, the chapters concerning trade unions were rewritten and a uniform notion of possession was introduced.

By this time, however, other European powers had overwhelmingly rejected the notion that the Pope had the right to convey sovereignty of regions as vast as the New World.

By defining the notion this way, Aristotle indicates that a truly tragic hero must have a failing that is neither idiosyncratic nor arbitrary, but is somehow more deeply imbedded -- a kind of human failing and human weakness.

By depicting slavery as benevolent, the museum's exhibits reinforced the notion that Jim Crow was a proper solution to racial tensions that had escalated during Reconstruction.

By the middle of the century, an attempt to be objective was made in poetry by the group of writers known as the Parnassians -- which included Leconte de Lisle, Théodore de Banville, Catulle Mendès, Sully-Prudhomme, François Coppée, José María de Heredia and ( early in his career ) Paul Verlaine -- who ( using Théophile Gautier's notion of art for art's sake and the pursuit of the beautiful ) strove for exact and faultless workmanship, and selected exotic and classical subjects which they treated with a rigidity of form and an emotional detachment ( elements of which echo the philosophical work of Arthur Schopenhauer whose aesthetic theories would also have an influence on the symbolists ).

By 1900 the notion of " building-as-cure " was largely discredited, and in the following decades these large facilities became too expensive to maintain.