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NOTES. 



NOTE 1, page 2. Diameter. A straight line passing through the centre, and 

 terminated both ways by the sides or surface of a figure, such as of a circle or 

 sphere. In fig. 1, q Q, N S, are diameters. 



NOTE 2, p. 2. Mathematical and mechanical sciences. Mathematics teach 

 the laws of number and quantity ; mechanics treat of the equilibrium and 

 motion of bodies. 



NOTE 3, p. 2. Analysis is a series of reasoning conducted by signs or symbols 

 of the quantities whose relations form the subject of inquiry. 



NOTE 4, p. 3. Oscillations are movements to and fro, like the swinging of 

 the pendulum of a clock, or waves in water. The tides are oscillations of the 

 sea. 



NOTE 5, p. 4. Grajitation. Gravity is the reciprocal attraction of matter 

 on matter; gravitation is the difference between gravity and the centrifugal 

 force induced by the velocity of rotation or revolution. Sensible gravity, or 

 weight, is a particular instance of gravitation. It is the force which causes 

 substances to fall to the surface of the earth, and which retains the celestial 

 bodies in their orbits. Its intensity increases as the squares of the distance 

 decrease. 



NOTE 6, p. 5. Particles of matter are the indefinitely small or ultimate 

 atoms into which matter is believed to be divisible. Their form is unknown; 

 but, though too small to be visible, they must have magnitude. 



NOTE 7> p- 5. A hollow sphere. A hollow ball, like a bomb-shell. A sphere 

 is a ball or solid body, such, that all lines drawn from its centre to its surface 

 are equal. They are called radii, and every line passing through the centre 

 and terminated both ways by the surface is a diameter, which is consequently 

 equal to twice the radius. In fig. 3, Qq or NS is a diameter, and C Q, CN 

 are radii. A great circle of the sphere has the same centre with the sphere 

 as the circles QEqd and QNgS. The circle AB is a lesser circle of the 

 sphere. 



NOTE 8, p. 5. Concentric hollow spheres. Shells, or hollow spheres, having 

 the same centre, like the coats of an onion. 



