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The Coriolis Effect

From The Flat Earth Wiki

A rotating Round Earth model predicts that bodies which move through the air will be appear to be deflected Eastwards or Westwards in their path of movement due to the rotation of the earth. This effect has been termed the "Coriolis Effect."

The Coriolis Effect, however, appears to be a fictitious effect that is not, and has never been, properly demonstrated with experimental evidence. Its proponents are unable to show that this effect has ever been detected or that it is truly necessary to account for in various operations. The evidence for this effect appears to be based entirely on 'common knowledge', on how things 'should be', and by authors who make 'predictions'; but all articles and documents presented in favor of the "Coriolis Effect" are without reference to, or demonstration of, the critical and necessary experimental evidence to directly prove the matter.

Origin of the Coriolis Effect

In an article titled History of the Coriolis Force (Archive) the origin story of the "Coriolis Effect" is described:

  “ The first detailed study on a manifestation of the "Coriolis" force was made by Giovanni Borelli in the 1660s, when he considered the problem of falling bodies on a rotating Earth. In a theoretical analysis, he found that they will undergo a small eastward deflection during their fall. ”


It has been alleged that the Coriolis Effect plays a part in the ballistic trajectory of artillery, and that artillerymen must account for it for accuracy. We are presented with military range tables for accounting for the Coriolis Effect, and so, it is speculated, the Coriolis Effect must be a real effect.

U.S. Army Artillery Coriolis Table Example

We are directed to the table from following document:

The Production of Firing Tables for Cannon Artillery (1967) (Archive)

Pg 103, Table H, Corrections to Range, in Meters, to Compensate for the Rotation of Earth:


When Coriolis Effect proponents are challenged on the accuracy or validity of this table, the proponents proclaim that if it were incorrect then artillery and artillerymen would be routinely inaccurate and miss their targets, and how could that be the case?

Artillery Ballistics Not Accurate

From the the introduction of the above paper provided to us we read that military artillery, which is purported to require adjustments for the "Coriolis Effect," is indeed, routinely inaccurate. The first round generally misses its target. Only after missing a number of times, and then adjusting the alignment of the cannon to compensate, does the artilleryman hit his or her target.

From the above 1967 artillery paper (Archive) we read:

  “ Ideally, a firing table enables the artilleryman to solve his fire problem and to hit the target with the first round fired. In the present state of the art, this goal is seldom achieved, except coincidentally. The use of one or more forward observers, in conjunction with the use of a firing table, enables the artilleryman to adjust his fire and hit the target with the third or fourth round fired. ”

In another artillery paper from 1973, we read a similar quote: (Archive)

  “ When today's field artillery firing tables are used with today's approved delivery techniques [as described in VM 6-401], accurate fire can be brought to bear on targets.

Such a statement can only be made because today's approved delivery techniques recognize that many errors (both precision and bias errors) exist and those techniques arc designed to minimize these errors. The techniques are not designed to produce first round hits, nor does the statement above infer that such hits can be achieved. ”

In 2016 a claimed expert named Guy Schuchman says that, despite GPS and modern improvements, the same problems exist today (Archive):

  “ It's extremely rare for the first round to hit the target. It's just too much data which not all of it can be measured in 100% accuracy and human errors are quite common: small offsets in calculating the coordinates of the target or the gun, small errors in calibration, humidity of the explosive propellant, etc.. The first round is just a test round. When it falls near the target it's the artillery observer's job to see how far and in what offset did it hit away from the target and provide the FDC with the data. ”

A 2017 paper by Australia's Armament Research Service admits the same: (Archive)

  “ Even though great effort is made to calculate the effect of environmental and ballistic variables, an unguided artillery projectile will not reliably strike the exact point at which it is aimed. Although artillerymen strive for first round accuracy, this will still be measured in tens of meters, and in deliberate targeting or combat engagements this introduces a degree of uncertainty when assessing the safety of friendly forces and non-combatants. Properly employed, artillery gun and mortar projectiles and rockets land in a predictable area (accuracy) in a non-predictable fashion (precision), and in common with small arms fire (especially machine guns), the employment of artillery systems yields a ‘beaten zone’ or field of fire into which rounds will fall. This zone is generally cigar-shaped with the long axis falling along the line from the gun to the target, as deviation tends to occur in range rather than azimuth. The length and breadth of the zone is range dependent, as with greater range, external factors have more time to exert influence on the projectile flight. ”

Sharp Shooting

It has been alleged that the Coriolis Effect also plays a part in accurate sharp shooting over long distances. However, we find several online references where claimed sniper veterans have stated that they have never taken the Coriolis Effect into account when shooting. We point to the U.S. Marine Corps, U.S. Army, and U.S. Navy SEAL sniping manuals, which do not mention the Coriolis Effect anywhere in their sniping texts at all.

Sniping Manuals

U.S. Marine Corps Sniping Manuals
1981 FMFM 1-3B Sniping (Archive)
2016 MCTP 3-01E Sniping

U.S. Army Sniper Field Training Manuals
1994 FM 23-10 Sniper Training
1989 TC 23-14 Sniper Training and Employment
2003 FM 3-05.222 Special Forces Sniper Training and Employment (Archive)

U.S. Navy SEAL Sniping Manual
US Navy SEAL Basic Sniper Training
US Navy SEAL Sniper Training Program

The sniper must know the general principles of: perspective, vanishing point, perspective drawing, delineation, and geographical areas of intelligence operations. However, the words "Coriolis" or "Coriolis Effect," do not appear anywhere in the U.S. Marine Corps, U.S. Army, or U.S. Navy SEAL sniper manuals.

Coriolis Not Found.png

The reader might ponder why the U.S. Military does not teach this allegedly important effect to its snipers.

Misleading References

The internet is rife with references that the Coriolis Effect is actively used, but this is an assumption without demonstration.

The World’s Longest Sniper Kill: The Enemy Shot Dead at 3,871 Yards (Over 2 Miles Away) (Archive)

  “ To understand the complexity of the shot, it’s best to start with a sniper maxim: sniping is weaponized math. Although a .50 caliber sniper rifle bullet can fly as far as five miles, a host of factors including gravity, wind speed and direction, altitude, barometric pressure, humidity and even the Coriolis Effect act upon the bullet as it travels. Even worse, these effects increase the farther the bullet travels. A successful sniper team operating at extreme distances must do its best to predict exactly how these factors will affect the bullet and calculate how to get the bullet back onto target. ”

This quote actually says "these are the factors that will affect the bullet," rather than "these are the factors that the sniper accounted for." One is a commentary by the author and the other is a depiction of process. The reader should be able to see and understand that there is a difference.

Deflection of Falling Bodies

From the 17th century well into the 19th century the deflection of falling objects was a hotly debated subject, and numerous experiments were conducted to study the landing path of bodies when dropped from high distances. To protect from the wind and elements the experiments were conducted within towers, high churches, and down underground mines and shafts.

From the History of the Coriolis Force (Archive) piece there is only one experiment which author of the article references in favor of the Coriolis Effect. All other papers referenced in the article appear to be theoretical analysis'.

  “ Only at the beginning of the 19th century were experiments done in a sufficiently careful manner to detect the deflection. For example,

J.F. Benzenberg (1804): Versuche über das Gesetz des Falls, über den Widerstand der Luft und über die Umdrehung der Erde nebst der Geschichte aller früheren Versuche von Galiläi bis auf Guglielmini, Mallinckbodt, Dortmund. ”

This is one of the Deflection of Falling Body Experiments. From 'The Report of the Sixteenth Meeting of the British Association of the Advancement of Science' (Archive) we find an analysis of Dr. Benzenberg's experiments:

  “ In the beginning of this century, Dr. Benzenberg undertook new experiments at Hamburgh, from a height of about 240 feet, which gave a deviation of 3·99 French lines; but they gave a still greater deviation to the south. Though the experiments here quoted seem to be satisfactory in point of the eastern deviation, I cannot consider them to be so in truth; for it is but right to state that these experiments have considerable discrepancies among themselves, and that their mean, therefore, cannot be of great value. In some other experiments made afterwards in a deep pit, Dr. Benzenberg obtained only the eastern deviation, but they seem not to deserve more confidence. Greater faith is to be placed in the experiments of Professor Reich, in a pit of 540 feet, at Freiberg. Here the easterly deviation was also found in good agreement with the calculated result; but a considerable southern deviation was observed. The numbers obtained were the means of experiments which differed much among themselves. After all this, there can be no doubt that our knowledge on this subject is imperfect, and that new experiments are to be desired. ”

In the book Earth Not a Globe, the author Samuel Birley Rowbotham devotes an entire chapter to the Deflection of Falling Bodies experiment saga.

Earth Not a Globe: Deflection of Falling Bodies

by Samuel Birley Rowbotham (Archive)

In this chapter Rowbotham walks us through numerous experiments, the inconsistencies among them, and concludes his chapter with:

  “ Thus it is admitted that deflection from a height of 300 feet "is so small as to be practically inappreciable;" that "great heights are necessary for giving only a deviation of one-tenth part of an inch;" that when this amount was observed, "at the same time deviation to the south was given, which was not in accordance with the mathematical calculations;" that "the experiments have considerable discrepancies among themselves;" that "the experiments differed very much;" that "after all there can be no doubt that our knowledge on this subject is imperfect;" that on repeating the experiments with the utmost possible care down a shaft of 1320 feet in depth, the bullets did not fall easterly at all from the plummets, "but from 10 to 20 inches south of the plumb-line," and out of forty-eight bullets, forty-four fell "on the south side of the shaft, in situations which precluded exact measurements of the distances being taken;" and, finally, that puzzled mathematicians, with their ever ready ingenuity to make facts agree with the wildest of theories, even with those of a opposite character, conclude that "falling bodies may have either north, south, east, or west deflection from the plumb-line." What value can such uncertain and conflicting evidence possess in the minds of reasoning men? They are shameless logicians, indeed, who contend that, from such results, the earth is proved to have a diurnal rotation! ”

Water Currents

Small Scale Water Currents

The rotation of small scale liquids in opposing hemispheres was debunked by Snopes (Archive).

Large Scale Water Currents

We find the assertion that large scale water currents rotate in accordance with the "Coriolis Effect" to be untrue. See Coriolis Effect (Weather)

Wind Currents

We find the assertion that the wind currents generally rotate in accordance with the "Coriolis Effect" to be untrue. See Coriolis Effect (Weather)


Many of these discussions against the Round Earth Theory are often and trivially won with a simple request of evidence. 'Mountains' of evidence are claimed to exist for phenomena such as this, yet when the Round Earth proponent is questioned in a simple and polite manner on the necessary demonstration, we find that the response is generally, to any reasonable standard, woefully insufficient. It is quite curious that this effect cannot be clearly demonstrated, and is so easily defeated with such simple questioning, despite our opponent's access to the vast collection of human knowledge that is the internet.

See Also