CONTENTS.

SECTION I.

PRELIMINARY DEFINITIONS AND EXPLANATIONS.

Definition of a fluid, 1; explanation of the term fluid pressure and

the definition of its measure, 2, 3, 4; a supposed solidification of a por-

tion of fluid does not affect its action upon the remainder, 5; hydrostatic

action of rigid surfaces upon fluids, 6; transmission of pressure by a fluid,

7; distinction between elastic and inelastic fluids, 8; measures of mass,

density, and specific gravity, 9, 10, 11, 12.

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II

Examples

SECTION II.

INELASTIC FLUIDS.

Definition of vertical and horizontal; pressure at a point in a heavy

fluid, 13; pressure uniform in the same horizontal plane, 14; free surface

horizontal, 15; common surface of two fluids which do not mix, 16;

heights of the free surfaces above this, 17; total normal pressure on a

surface immersed, 18; resultant of the same pressure, 19; conditions

which a floating body satisfies, 20; stable, unstable and neutral equilibrium,

21; conditions of a body's sinking, rising, or remaining stationary when

immersed totally in a fluid, 22, 23, 24, 25; Hydrostatic Balance, 26;

methods for finding the specific gravity of a body or fluid, 27, 28, 29, 30;

Common Hydrometer, 31; Nicholson's Hydrometer, 32; specific gravity

of a mixed fluid, 33.

Examples, 31

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43

SECTION III.

ELASTIC FLUIDS.

Pressure in elastic fluids sometimes termed elastic force, 34; assumed

to be uniform under certain conditions, 35; Barometer, 36; Boyle's Law,

37; pressure varies as the density, 38; to find k for air, 38*; law of

density in the atmosphere, 39; barometer employed to measure heights,

40; Air-Pump, 41; density after the nth stroke, 42; causes limiting the

exhaustion, 43; Hawksbee's air-pump, 44; Smeaton's ditto, 45; the Con-

denser, 46; Common Pump, 47; tension of its piston-rod, 48; Lifting

Pump, 49; Forcing Pump, 50; Bramah's Press, 51; Siphon, 52, 53;

Diving-Bell, 54; Atmospheric Steam Engine, 55; Watt's improvements,

56; Double-Action Steam Engine, 57.

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85

SECTION IV.

GENERAL PROPOSITIONS.

Virtual Velocities, 58; resolved parts of normal pressures upon the

surface of a vessel containing heavy fluid, 59, 60, 61, 62; ditto, when the

included fluid is elastic, 63; Center of Pressure, 64; Barker's Mill, 65;

free surface of a revolving fluid under certain conditions, 66; resultant

pressure upon the surface of a body immersed in any fluid whatever, 67;

tension at any point in a solid how measured, 68; tension at any point of

a cylindrical surface containing fluid, 69, 69*; ditto for a spherical

surface, (694), (694*); mode of graduating a barometer, 70, 71, 72;

Wheel Barometer, 73.

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Examples, 104

112

SECTION V.

MIXTURE OF GASES.-VAPOUR.

Boyle's law holds for a mixture of gases, 74; gas absorbed by a liquid

in contact with it, 75; relation between change of temperature and change

of volume in all substances, 76; meaning of the term thermometer,

77; mercurial thermometer, 78; filling the thermometer; comparative

expansions of substances, 79; temperature measured by the thermometer,

80; expansion of water, 81; proof of the formula p= kp(1 + at), 82;

relations between the heat absorbed, the resulting temperature and the

mass, for a uniform substance, 83; algebraical expression of the same,

84; ditto for a compound substance, 85; specific heat, 86; algebraical

formula, 87; specific heat of gases, 88; all substances made to ex-

perience the solid liquid or gaseous state by the application of correspond-

ing amount of heat, 89; vapour, 90; saturation density, and its dew-

point, 91; under what circumstances vapours follow Boyle's law, or not,

92; gases, 93; the preceding results independent of the number of gases

present, 94, 95; ebullition of water, 96; algebraical formula connecting

the pressures and temperatuure for a mixture of gas and vapour, 97; latent

heat, 98; effects produced by absorption of heat in evaporation, 99; con-

traction produces the opposite results to dilatation, 100; hygrometrical

state of the atmosphere; 101; Clouds, 102; Rain, 103; causes producing

these effects, 104; Snow and Hail, 105; Dew, Hoar-frost, &c., 107; Con-

duction, Convection, and Radiation of heat, 108; cause of dew, &c., 109;

Dew-point, 110; results of the law of expansion in water, 111.

General Examples.

Answers to the Examples

113

HYDROSTATICS.

SECTION I.

PRELIMINARY DEFINITIONS AND EXPLANATIONS.

1. DEF. A fluid is a collection of material particles so situated in contact with each other as to form a continuous mass, and such that the application of the slightest possible force to any one of them is sufficient to displace it from its position relative to the rest.

That part of Statics, where a fluid appears as the principal means of transmission of force, is termed Hydrostatics. The law of that transmission must, like the law of transmission by a rigid body, by a free rod or string, or by contact of surfaces, &c., be established by experiment.

The mutual forces called into action by the contact of surfaces are in Statics called pressures: this term is used in the same sense in Hydrostatics, where it is applied to denote the forces of resistance, which adjacent particles of the fluid exert, either upon one another, or upon rigid surfaces in contact with them. The nature of the reaction between a rigid surface and a fluid in contact with it might perhaps be arrived at by the aid of analysis from the above definition. But such an investigation, even if entirely satisfactory in itself, would

P. H.

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