The bullroarer, rhombus, or turndun, is an ancient ritual musical instrument and a device historically used for communicating over greatly extended distances.

It makes a characteristic roaring vibrato sound with notable sound modulations occurring from the rotation of the roarer along its longitudinal axis, and the choice of whether a shorter or longer length of cord is used to spin the bullroarer.

Traditional Navajo music is always vocal, with most instruments, which include drums, drumsticks, rattles, rasp, flute, whistle, and bullroarer, being used to accompany singing of specific types of song ( Frisbie and McAllester 1992 ).

The primitive bullroarer is an unframed free reed ; it consists simply of a stone or board of wood tied to a rope which is swung around through the air to make a whistling sound.

On their way back they heard the sound of a bullroarer, and as they searched for the source of the noise they caught sight of a sandhill wallaby.

By modifying the expansiveness of its circuit and the speed given it, and by changing the plane in which the bullroarer is whirled from horizontal to vertical or vice versa, the modulation of the sound produced can be controlled, making the coding of information possible.

His voice can be heard through the medium of the bullroarer which is whirled through the air during initiation ceremonies.

The bullroarer must be cut from a tree which contains his spirit for it to work.

His hunger sated, he lay down to sleep again and a bullroarer emerged from under his armpit.

Instruments in which the vibrating air is not contained within the instrument, for example sirens, or the bullroarer.

The bullroarer is one example.

The Librarian meanwhile steals the Creator's bullroarer and spins it, causing the drought Rincewind is in the process of stopping.

Rincewind lets go and the bullroarer flies off ; immediately, it begins to rain.

Having saved Fourecks, Rincewind and the Wizards return to Ankh-Morpork by ship, and the story ends with the old man with the sack ( the Creator of the last continent ) catching the bullroarer in front of a young boy.

In fact, when the bullroarer is whirled around one's head in a horizontal plane, the pitch rises and falls in its usual manner even though the spinning neither approaches much nor retreats much from the ears of the whirler.

There is no necessary link between a bullroarer's pitch and how fast the entire bullroarer is going around on its cord in its large circle, or where the blade is at any given time in relation to a hearer, or whether it is approaching or receding from that listener.

In fact, two listeners on opposite sides of the person whirling the bullroarer will hear simultaneous and nearly identical rises and falls of the pitch even though the blade will be approaching one and going away from the other at any given time.

A bullroarer consists of a weighted aerofoil ( a rectangular thin slat of wood about ( 6 in ) to ( 24 in ) long and about ( 0. 5 in ) to ( 2 in ) wide ) attached to a long cord.

He opens these gateways by whirling his bullroarer over his head.

The role the bullroarer play in the creation and functioning of the gateways is unclear.

The trance induction central to the cult involved not only chemognosis, but an " invocation of spirit " with the bullroarer and communal dancing to drum and pipe — much like modern-day raves.

On the other hand, the bright vision of the future has been directly stated in science fiction concerned with projecting ideal societies -- science fiction, of course, is related, if sometimes distantly, to that utopian literature optimistic about science, literature whose period of greatest vigor in the late nineteenth and early twentieth centuries produced Edward Bellamy's Looking Backward and H. G. Wells's A Modern Utopia.

After selecting a sheet and inspecting it for flaws ( even the best sometimes has foreign ' nubbins ' on its surface ), I sponge it thoroughly on both sides with clean, cold water.

Nevertheless, because the Cost Section has felt impelled to make some kind of a distribution of total costs, it has apportioned this residue, which it sometimes calls `` burden '', among the units of carload traffic on a basis ( partly ton, partly ton-mile ) which is concededly quite arbitrary from the standpoint of cost determination.

The term " the United States " has historically been used, sometimes in the plural (" these United States "), and other times in the singular, without any particular grammatical consistency.

After the records of the property have been traced and the title has been found clear, it is sometimes guaranteed, or insured.

No neuron ever has more than one axon ; however in invertebrates such as insects or leeches the axon sometimes consists of several regions that function more or less independently of each other.

The Paris – Bordeaux – Paris race of June 1895 has sometimes been erroneously described as the " first motor race ", despite the 1894 event being decided by speed and finishing order of the eligible racers.

It has been maintained that the right to wear mitres was sometimes granted by the popes to abbots before the 11th century, but the documents on which this claim is based are not genuine ( J. Braun, Liturgische Gewandung, p. 453 ).

An increase in literacy has, historically, sometimes spawned a trend toward abbreviation.

Each atom has, in general, many orbitals associated with each value of n ; these orbitals together are sometimes called electron shells.

This usage has been regarded as Eurocentric by some, and the alternative terms Lesser Antarctica and Greater Antarctica ( respectively ) are sometimes preferred.

The early detailed source, the Germania of Tacitus, has sometimes been interpreted in such a way as to provide yet other historical problems.

Many agates are hollow, since deposition has not proceeded far enough to fill the cavity, and in such cases the last deposit commonly consists of drusy quartz, sometimes amethystine, having the apices of the crystals directed towards the free space so as to form a crystal-lined cavity or geode.

It is a popular snack sold in Mexico, sometimes mixed with chocolate or puffed rice, and its use has spread to Europe and parts of North America.

Historically, this has sometimes been the only way to allocate " dynamic memory " portably.

The fact that judgments of beauty and judgments of truth both are influenced by processing fluency, which is the ease with which information can be processed, has been presented as an explanation for why beauty is sometimes equated with truth.

Malraux argues that, while art has sometimes been oriented towards beauty and the sublime ( principally in post-Renaissance European art ) these qualities, as the wider history of art demonstrates, are by no means essential to it.

However, the resurgence of expeditionary warfare in the past twenty years has seen the emergence of gun-armed wheeled vehicles, sometimes called protected gun systems, which may bear a superficial resemblance to tank destroyers, but are employed as direct fire support units typically providing support in low intensity operations such as Iraq and Afghanistan.

The Greek mathematician Menaechmus solved problems and proved theorems by using a method that had a strong resemblance to the use of coordinates and it has sometimes been maintained that he had introduced analytic geometry.

Alexis Korner ( 19 April 1928 — 1 January 1984 ) was a blues musician and radio broadcaster, who has sometimes been referred to as " a Founding Father of British Blues ".

However, the resurgence of expeditionary warfare in the past twenty years has seen the emergence of gun-armed wheeled vehicles, sometimes called protected gun systems, which may bear a superficial resemblance to tank destroyers, but are employed as direct fire support units typically providing support in low-intensity operations such as the wars in Iraq and Afghanistan.

This has led to a tradition of a cappella singing sometimes known as sefirah music.

As an explicitly spiritual movement, anthroposophy has sometimes been called a religious philosophy.

* The equipment available to observation teams has progressed from just prismatic compass, hand-held or tripod mounted binoculars and sometimes optical range-finders.