## Mechanism of the HeavensJ. Murray, 1831 - 621 pages |

### From inside the book

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Page 28

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**substituted**in the general equation of the motion of a particle on its surface , it becomes dy δα + dt dex δ . υ = dt dez δу + δα + λδα = 0 . dt2 But du does not enter into this equation when the particle is free ; and when it must move ... Page 34

... ds vdt , whence dt = ds v therefore ds is constant ; and when this value of dt is

... ds vdt , whence dt = ds v therefore ds is constant ; and when this value of dt is

**substituted**in equation ( 7 ) , in consequence of the values 34 [ Book I. VARIABLE MOTION . Pressure of a Particle moving on a curved Surface. ... Page 41

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**substituted**in dz = udx , it will furnish a new equation of the first order between z , x , and t , which will be the differential equation of the trajectory . If the resistance of the medium be zero , h = 0 , and the preceding equation ... Page 74

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**substituted**in the preceding equation , it becomes , with regard to the plane roy , - Σ.m ( rdy - yd'r ) = Em . ( tV - yX ) . dt2 = . ( Y In the same manner - zdr xd2 Ση . = 74 [ Book I. MOTION OF A SYSTEM OF BODIES . Page 75

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**substituted**in the preceding equations , F vanishes ; the same may be shown with regard to m ' , m " , & c . Hence the equations of areas are reduced to Ση Ση { yd x dt - xd y } = 0 = 0 , zd x dt xd z } Em Sydz - zd3y and their ...### Other editions - View all

### Common terms and phrases

A₁ action angle ascending node attraction axes axis becomes c'mv centre of gravity centrifugal force co-ordinates coefficients comets computed conic sections consequently cosines curve density depending determined differential direction disturbing forces dR dR dt dt earth eccentricity ecliptic elements epoch equal equilibrium equinoxes fixed plane fluid functions give hence inclination indefinitely small integral Jupiter latitude mass mean anomaly mean distance mean longitude mean motion moon moon's move nearly observation omitted orbit of Jupiter oscillations parallax particle perigee perihelion periodic inequalities perturbations planets preceding equation radius vector ratio regard retrograde motion rotation satellites Saturn secular inequalities secular variations sidereal sine spheroid square substituted surface system of bodies terrestrial theory tion true longitude Uranus velocity whence zero δα δε δυ

### Popular passages

Page xviii - ... that the mean longitude of the first satellite, minus three times that of the second, plus twice that of the third, is always equal to two right angles.

Page vii - His works, but trace, with precision, the operation of His laws, use the globe he inhabits as a base wherewith to measure the magnitude and distance of the sun and planets, and make the diameter of the earth's orbit the first step of a scale by which he may ascend to the starry firmament. Such pursuits, while they ennoble the mind, at the same time inculcate humility, by showing that there is a barrier which no energy, mental or physical, can ever enable us to pass: that, however profoundly we may...

Page xv - That day, as other solemn days, they spent In song and dance about the sacred hill ; Mystical dance, which yonder starry sphere Of planets, and of fix'd, in all her wheels Resembles nearest, mazes intricate, Eccentric, intervolved, yet regular Then most, when most irregular they seem ; And in their motions harmony divine So smooths her charming tones, that God's own ear Listens delighted.

Page xlix - An account of experiments for determining the length of the pendulum vibrating seconds in the latitude of London.

Page lxiv - Jupiter ; it then gradually diminished in splendor, and having exhibited all the variety of tints that indicate the changes of combustion, vanished sixteen months after its discovery, without altering its position. It is impossible to imagine anything more tremendous than a conflagration that could be visible at such a distance.

Page xiv - But, in the midst of all these vicissitudes, the length of the major axes and the mean motions of the planets remain permanently independent of secular changes. They are so connected by Kepler's law, of the squares of the periodic times being proportional to the cubes of the mean distances of the planets from the sun, that one cannot vary without affecting the other.

Page lxix - If the attraction of the sun for the огпtre of the earth, and of the hemisphere diametrically opposite to him, were diminished by a difficulty in penetrating the interposed matter, the tides would be more obviously affected. Its attraction is the same also, whatever the substances of the celestial bodies may be; for if the action of...

Page vi - is to inspire the love of truth, of wisdom, of beauty — especially of goodness, the highest beauty — and of that supreme and eternal Mind, which contains all truth and wisdom, all beauty and goodness. By the love or delightful contemplation and pursuit of these transcendent aims, for their own sake only, the mind of man is raised from low and perishable objects, and prepared for those high destinies which are appointed for all those who are capable of them.

Page xii - ... depends upon the velocity with which they were first propelled in space. Had that velocity been such as to make the planets move in orbits of unstable equilibrium, their mutual attractions might have changed them into parabolas, or even hyperbolas, so that the earth and planets might, ages ago, have been sweeping far from our sun through the abyss of space.

Page xxxvi - ... the waters back to their sources ; and thus again by removing matter to a greater distance from the centre, destroy the velocity generated by its previous approach ; so that the descent of the rivers does not affect the earth's rotation.