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Perpendicular

Denoting the latest stage of English Gothic church architecture, prevalent from the late 14th to mid 16th centuries and characterized by broad arches, elaborate fan vaulting, and large ...

Agricultural Technology

Agricultural Technology   Reference library

Alan L. Olmstead and Paul W. Rhode

The Oxford Encyclopedia of the History of American Science, Medicine, and Technology

Reference type:
Subject Reference
Current Version:
2015

...including a multibottom riding plow and improved planters, advanced farm productivity. The spread of check row planters following the Civil War made it possible to drop seeds at uniform distances in straight lines. This allowed horse-drawn cultivators to operate in perpendicular directions when weeding fields. This system both saved labor and increased yields. Mechanical corn pickers were commercialized relatively late and began to diffuse only in the late 1920s when coupled with tractors. Corn holds a special place in the traditional history of...

parallax

parallax   Reference library

The Oxford Companion to the History of Modern Science

Reference type:
Subject Reference
Subject:
Science and technology, History of Science
Length:
496 words

...an estimated distance to a group of stars. Assuming that the group members have random movements, the average of the measured radial velocities (line-of-sight components, corrected for the observer's movement) equals any other component, including that perpendicular to the line of sight. This average perpendicular velocity, combined mathematically with its corresponding average observed angular change (proper motion), yields an average distance. See also Astronomy ; Copernicus, Nicholas . Norriss S. Hetherington , Science and Objectivity: Episodes in the...

mass spectrograph

mass spectrograph   Reference library

The Oxford Companion to the History of Modern Science

Reference type:
Subject Reference
Subject:
Science and technology, History of Science
Length:
630 words

...But it was Aston, working in the Cavendish Laboratory at Cambridge under Ernest Rutherford , whose name became linked with the mass spectrograph. The two instruments relied on different focusing techniques and produced different types of results. In Aston's mass spectrograph perpendicular electric and magnetic fields focused ions with different masses at different points on a photographic plate. Aston identified and measured the atomic weights of a large number of isotopes; established the “whole number rule” for atomic weights (that isotopic masses are...

sundial

sundial   Reference library

The Oxford Companion to the History of Modern Science

Reference type:
Subject Reference
Subject:
Science and technology, History of Science
Length:
549 words

...projected onto the horizontal or vertical plane. Such a dial works throughout the year without adjustment; it does not depend on solar declination since each daily path of the sun takes place in a plane perpendicular to the gnomon, but it will be accurate in only one latitude. If the hour lines are placed on a plane parallel to the equator and perpendicular to the gnomon, they will be equally spaced and the dial easily adjusted for latitude, which makes the “equatorial” or “equinoctial” dial appropriate to portable dials in various forms. Horizontal dials can...

computerized tomography

computerized tomography   Reference library

The Oxford Companion to the History of Modern Science

Reference type:
Subject Reference
Subject:
Science and technology, History of Science
Length:
638 words

...tomography . In the 1920s, innovators in several different countries devised methods of using X rays to obtain an image of a planar cross-section (P) in the interior of the body. The rays were directed obliquely through P to a film plate placed perpendicular to the body's vertical axis and at a height such that the rays through the center of the plane would strike the center of the plate. The body was rotated around its vertical axis and the film plate rotated in synchronization with it around a parallel axis but in the opposite sense. The rotation...

geodesy

geodesy   Reference library

The Oxford Companion to the History of Modern Science

Reference type:
Subject Reference
Subject:
Science and technology, History of Science
Length:
1,395 words

...verticals necessary for finding latitudes. They came to agree that no fiddling would fit their knowledge to an ellipsoid; the shape of the earth was just that, the earth's shape, a “geoid,” defined by Carl Friedrich Gauss and other leading geodecists as a surface everywhere perpendicular to the direction of gravity. Beginning in 1787 with the linkage of the meridians through Greenwich and Paris via a series of triangles that crossed the channel, Europe gradually approached unification, trigonometrically speaking. The French furthered unification by running...

star

star   Reference library

The Oxford Companion to the History of Modern Science

Reference type:
Subject Reference
Subject:
Science and technology, History of Science
Length:
1,035 words

...Halley convinced themselves (between 1692 and 1720 ) that the starry realm was infinite, and balanced by gravitation. The discovery of the Doppler principle in 1842 revolutionized the study of stellar motion. Radial velocities could then be combined with proper motions perpendicular to the line of sight. In the second half of the nineteenth century, photography further transformed stellar research. Photographic spectra came in 1872 and photographic cataloguing and sky mapping in 1882 . Earlier, around the turn of the century, William Herschel had...

mechanics

mechanics   Reference library

The Oxford Companion to the History of Modern Science

Reference type:
Subject Reference
Subject:
Science and technology, History of Science
Length:
2,233 words

...of moving bodies would behave if the system moved along noninertial curves ( 1742 ). Gaspard Gustave de Coriolis showed ( 1835 ) that the Newtonian laws of motion apply in a rotating reference frame if the equations of motion include a “Coriolis acceleration” in a plane perpendicular to the axis of rotation, a kinematic acceleration which Coriolis interpreted as an extra force (the “Coriolis force”) and which became important in ballistics and meteorology. An important step in the formalization of mechanics was Heinrich Hertz 's attempt to remove...

optics and vision

optics and vision   Reference library

The Oxford Companion to the History of Modern Science

Reference type:
Subject Reference
Subject:
Science and technology, History of Science
Length:
2,115 words

...( See Electromagnetism ). British physicists attempted to ascertain the physical properties of this ubiquitous and omnicompetent ether. To incorporate polarization into the theory, both Young and Fresnel independently suggested that the vibrations constituting light are perpendicular to the direction of travel, not, as in the model proposed by Huygens and, originally, Young, in the direction of travel, as is the case of sound in air. With this addition, the wave theory bettered the corpuscular theory at its strongest point. All efforts to find a mechanical...

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