6 INTRODUCTION TO PHYSICS. [MECHANICAL PHILOSOPHY, Bra 



experiments on these subjects will be introduced. The action of the material and cargo of ships on the compass will 

 be explained, so far as modern Science has brought light on that intricate subject. 



ELECTRO-MAGNETISM. This branch of Science is of very recent' origin ; and its chief application, the electric 

 telegraph, has made it, so far, the most popularly known of any. The production of magnetic effects in soft iron, the 

 mutual action of Klectric and Magnetic Currents, the divergence of the Magnetic Needle, and the various applications 

 of these effects, such as the Electric Telegraph, both on land and through water, together with Electro-Magnetic 

 Mii.-hmes, will be found in this section. Ruhmkorfs new Induction Coil, and various experiments with it, will be 

 explained. 



ACOUSTICS. The four agents, Heat, Light, Electricity, and Magnetism, are at present supposed to be produced 

 by motion of an undulatory nature ; and much analogy exists between them and the production of sound. Under 

 the head of ACOUSTICS, this connection will be considered ; together with the conveyance and reflection of Sound, 

 Echoes, Musical Instruments, and other allied subjects. 



CHEMISTRY. The most casual observation will at once suggest that there must exist a vast variety of substances 

 in nature, having qualities greatly differing from each other. It is the object of Chemistry to discover these 

 qualities, and to examine their mutual relationship. In dealing with this branch of Science, the chemical his- 

 tory of Inorganic Bodies will be first considered. The Chemistry of Life, both vegetable and animal, Agricultural 

 Chemistry, and Chemical Analysis, will follow in order ; and the subject will be made complete by an extended 

 notice of the numerous applications of chemistry employed in the arts, manufactures, and in mining and metallurgy. 



MATHEMATICS. The object of Mathematical Science is to point out the different relations of Number, Time, 

 and Space. Arithmetic, Algebra, Logarithms, and Logarithmic Tables of Natural Numbers ; Geometry, Plane 

 and Spherical ; Trigonometry ; and the application of these, under the heads of Practical Geometry and Mensura- 

 tion, will be all fully investigated in this section : and each branch will be so treated as to enable the student to 

 master the majority of problems which occur in the application of Mathematics to the investigations of Physical 

 Science. Every endeavour will be made to combine simplicity of expression with scientific instruction. 



MECHANICAL PHILOSOPHY, or APPLIED MATHEMATICS. Under the head MECHANICS, the Laws of Motion and 

 Force, as applied to Machinery, will be first considered ; with mechanical contrivances for economising labour, or 

 for producing motive power, including Steam-Engines, <fec. Implements of husbandry and trade, and other similar 

 mechanical inventions, will be fully described ; and their essential peculiarities also pointed out. Rules for calcu- 

 lating the power of engines, the weight of machinery, its regulation, and other interesting facts, will be included, 

 so as to make this section of value to the practical man. 



HYDROSTATICS and HYDRAULICS. The different fluids which are generally typified by water ; the laws which 

 govern them when at rest or in motion ; the application of these laws, as in Water- Wheels, <fcc. ; the flow of Water 

 through pipes ; the construction of Canals and Reservoirs ; the Hydraulic Press, and many allied matters, will be 

 dealt with under this head. 



PNEUMATICS. The laws which govern air and other gases are generally included in this branch of Science. 

 Beside explaining the causes of many atmospheric phenomena, we shall here give descriptions of the Barometer, 

 Pumps, Air-Engines, and other inventions which depend on the application of the laws of air or gasiform bodies. 



ASTRONOMY. The consideration of the subjects to which we have hitherto alluded, necessarily attaches the mind 

 to objects of terrestrial interest. In the study of Astronomy, we are led beyond all mundane influence, and seem 

 to take so high a stand in nature as to be enabled to have an extended survey of the works of the Creator. For 

 sublimity of subject and range of observation, Astronomy stands immeasurably beyond every other branch of Science. 

 Even a superficial view of its truths is deeply interesting to the intelligent mind. But our object will extend further. 

 It will be our endeavour to give an insight into those laws by which the constitution and motion of the Heavenly 

 Bodies are governed. Whilst a popular description of Astronomical Science will be afforded, the mathematical student 

 will have an opportunity of investigating the truths and bases on which the leading theories of this noble branch of 

 Science are founded. It is impossible to enumerate here the varied matters which we shall have to speak of. The 

 Sun, the Planets, the Earth, and Moon ; their motions in their orbits and on their axes ; the causes of the Tides, 

 of Eclipses ; the nature and motion of Comets ; the Constellations and Fixed Stars, <fec. , will be dealt with, so as to 

 interest both the general and advanced reader ; and in a way which, we trust, will add the element of intelligence 

 to the natural admiration which all feel when they " consider the heavens," the handiwork of GOD. 



NAVIGATION and NAUTICAL ASTRONOMY. Nothing is of greater importance to the navigator than a knowledge 

 of Astronomy. By it he is enabled to trace his path on the sea with a certainty which seems truly marvellous. The 

 heavenly bodies are as celestial lighthouses to him ; and, by observing their positions, he is enabled to calculate his 

 exact place on the surface of the earth. The subject will be dealt with in an essentially practical manner ; and 

 ample rules will be given for calculating, arithmetically and by logarithms, the leading problems of this branch of 

 Science ; such as Latitude, Longitude, errors caused by Refraction, Departures, Courses, and allied subjects. The 

 relations between Astronomy and Navigation will thus be fully pointed out, and varied practical matter will also 

 be introduced in this section. 



With some of the subjects named above, tables of various kinds will be required ; and these have been accord- 

 ingly supplied in each section, so that the student will have no occasion to refer to other works. 



METEOROLOGY. This interesting and almost new branch of Natural Science, gives an explanation of the various 

 phenomena which occur in our atmosphere. Amongst these may bo named Wiud, Water-Spouts, Rain, Hail, 

 Snow, Thunder and Lightning, the Aurora Borealis, aud Shooting Stars, Dew, Moisture, Evaporation, Clouds, <fec. 

 We shall include an ample description of the different modes adopted for the purpose of observing and registering at- 

 mospheric changes, and give directions for ascertaining the approach of storms, cyclones, <fec. ; referring also to the lata 



