HALLEY, EDMUND, astronomer and mathematician, born near London; determined the rotation of the sun from the spots on its surface, and the position of 350 stars; discovered in 1680 the great comet called after his name, which appeared again in 1825; was entrusted with the publication of his "Principia" by Sir Isaac Newton; made researches on the orbits of comets, and was appointed in 1719 astronomer-royal (1656-1742).
This preponderating repulsive effect may be utilized or may show its presence by producing movement or pressure in a given direction, by producing angular deflection as of a pivoted body, or by producing continuous rotation with a properly organized structure.
To entail irreversible poverty upon generation after generation, only because the ancestor happened to be poor, is, in itself, cruel, if not unjust, and is wholly contrary to the maxims of a commercial nation, which always suppose and promote a rotation of property, and offer every individual a chance of mending his condition by his diligence.
His telescope discovered the moons of Jupiter, and his observation of the spots in the sun confirmed the earth’s rotation.
Let us consider only the rotation of the earth on its axis, the tide-speed of day and night.
So exactly is the clockwork or its substitute adapted to counteract both the rotation and revolution of Mars, that the two images underwent no other change of place than that caused by their own proper motion in space; a movement which, notwithstanding the immense magnifying power employed, was of course scarcely perceptible.
The simplicity and directness of his character, his quick sympathy and thoughtless generosity, and his delicate sense of honor unfitted him for such a scramble as that which degrades the quadrennial rotations of our Departments.
Ptolemy accepted the spherical form of the earth but denied its rotation or any other movement.
These markings enabled us to follow with clear ocular appreciation the rapid rotation of this planet.
On the wheat lands, summer fallow, wheat, and clover pasture, form the three years' rotation.
I do not say that the nature of light consists in very small round globules; nor of whiteness in such a texture of parts as gives a certain rotation to these globules when it reflects them: for I am not now treating physically of light or colours.
This would correct the error mentioned if it existed, and shows also that no constant errors were introduced by having the rotation constantly in the same direction, the results in both cases being almost exactly the same.
His crops of wheat, in which he especially put faith, and which he grew year after year upon the same land, totally ignoring the ancient rotations, were the wonder of the neighbourhood.
There is a further condition, upon which I cannot enter into detail just now, but which may be understood in a general way when I say that it is a condition of either uniform or of increasing molecular rotation from the surface inward, analogous to the condition that the density of a liquid, resting for example under the influence of gravity, must either be uniform or must be greater below than above for stability of equilibrium.
He is in command of living natureof the rotation of seasons, of wind, frost, rain; he uses them to provide food for those that hunger and must be fed.
Good culture, which means rotation, deep ploughing, farms well stocked, and some manure applied at intervals of from three to five years, would, in good seasons, very often approach these latter figures.
The organic and environic rearrangements incident to obscure rotations in higher space are like the changes a mirror-image undergoes as an object draws near and then recedes from its plane.
"Failure to practise crop rotation is undoubtedly one of the main explanations for the general prevalence of smut in the wheat-fields of eastern Washington.
The point at which the outer and inner portions of the float just balance one another in propelling effect, is called the centre of pressure; and if all the resistances were concentrated in this point, they would have the same effect as before in resisting the rotation of the wheel.
A series of treatises is devoted to subjects in natural science: The Effect of the Tides in retarding the Earth's Rotation; The Obsolescence of the Earth; Fire (Inaugural Dissertation), Earthquakes, and the Theory of the Winds.
The extractor is so connected with the bolt head as not to share the rotation of the latter when the handle is turned down into the locking position.
You stop the rotation of the earth, you know.
Those to whom the less agreeable employments were assigned rebelled or murmured, and at last it was necessary to substitute rotation for division of labour, since no one would admit that he was best fitted for the lower or less agreeable.
Agricola no doubt made the Roman yoke easier upon the necks of the conquered people, and suggested the rotation of crops.
But the chief point of interest in this device lies in the combination with the lever of a brake, enabling the operator, by a simple reversal of the treadle's motion, to instantly suspend the rotation of the machine.