3036
THE NEW ZEALAND GAZETTE.
[No. 98

sity of light; effect of varying the distance of a luminous point; shadows and penumbræ; eclipses; photometry. Experiments demonstrating the laws of the reflection of light; plane mirrors; the sextant. Concave spherical mirrors; distinction between real and virtual images; to determine the principal focus by experiment and from the radius of the mirror; · experimental illustration of conjugate foci. Experiments illustrative of the laws of single refraction; effects of refraction; transmission of light through a plate, a prism, and a lens. Convex lenses; to determine the principal focus by experiment; experimental illustration of conjugate foci. Simple optical instruments; the camera obscura; the eye. The composition of light; the spectrum; colour.

(20.) Magnetism and Electricity.—Candidates will be expected to show an experimental as well as a theoretical knowledge of the fundamental laws of magnetism and electricity, but will not be expected to show any further knowledge of pure mathematics than what is demanded in subject (17) Elementary Mathematics.

Magnetism: Natural and artificial magnets; parts and properties of bar and horse-shoe magnets; tests of permanent magnetization; attraction and repulsion; mutual action of poles of two magnets of equal strength; astatic system; the various ways of using permanent magnets for magnetizing steel bars; graphic representation of the distribution of free magnetism along a bar magnet, and of its lines of force; magnetic influence; the action of a magnet on soft iron and on steel at varying distances; keepers, and their use; magnetization of a steel ring; the directive action of the earth on magnetic needle free to swing in a horizontal or in a vertical plane. The magnetic meridian at a place, and the determination of it; influence of the earth’s magnetism on soft iron.

Statical Electricity: The two kinds of electrification, their simultaneous and equal development and their mutual reactions; conductors and non-conductors; electrification by contact; influence of a charged body on earth-connected and on insulated bodies; “free” and “bound” electricity. Gold-leaf electroscope; the electrification of it by contact and by influence; the interpretation of its indications; use of it in examining the seat and distribution of charges on solid and on hollow conductors of various shapes. The electrophorus and friction electrical machines; action of sharp points.

Current Electricity: Fundamental experiments—Action of dilute sulphuric acid on strips of (a) commercial zinc, (b) pure or amalgamated zinc, (c) copper, (d) pure or amalgamated zinc and copper, before and after external contact between the strips. The simple voltaic cell, its parts and action; the external and internal circuit. Elementary notions of electro-motive force; resistance and strength of current and the relation between them; the volt, ohm, and ampere. Best shape and arrangement of the parts of a cell; causes of the weakening of the current, and the remedies adopted. Description of the common forms of voltaic cells; conditions which a good cell should fulfil. Effect of current in (a) a straight wire, (b) a looped wire, on a magnetic needle, and thence the determination of the direction of the current in any wire; the galvanoscope and its use in detecting changes in the strength of a current, and in comparing (roughly) the strengths of different currents or the resistances of wires and liquids; magnetic properties of a coiled conductor; the effect of introducing a soft-iron core; electro-magnets; resistance of conductors; heating effect of current; incandescent lamps; chemical effect of current; elementary notions of electrolysis.