SCIENCE IN SECONDARY SCHOOLS, 165 
C. General Physics. 
1. How ships float. Measurement of extra displacement produced by adding 
‘cargo’ to a box floating in water suggests Archimedes’ Principle. Confirma- 
tion in case of other liquids. Extension of principle to bodies that sink. Use 
of camels and pontoons. Submarine boats. Balloons and airships; contrast with 
aeroplane. 
Exercises on use of Archimedes’ Principle in determining volumes and specific 
gravities. 
2. The barometer as a meteorological instrument. Construction of siphon 
barometer. Pascal’s theory of action illustrated by demonstrating increasing 
pressure at lower depths in a jar of water. The experiment of the Puy de 
Dome. Reduction of barometer readings to sea-level for construction of 
barometric charts. Relation between isobars and winds. 
Boyle’s experiments in confirmation of Pascal; leading to notion of the 
‘spring’ of the air and to Boyle’s Law. 
Experiments and apparatus illustrating air-pressure : pumps, vacuum-brake, 
parcel-transmitter, siphon, &c. The aneroid barometer: its use in determining 
heights in mountaineering, aeroplaning, &c. 
Archimedes’ Principle explained by theory of liquid-pressure. The theory 
applied to explain water-supply systems, hydraulic lifts and engines. 
3. Capillarity. Experiments to supplement those of I., C., 1. Measurement 
of surface tension (in grams-weight per cm.) by rise of water in tube. Simple 
study of bubbles, drops, and jets; also of common phenomena such as writing 
with ink. 
4. Osmosis. Simple experiments to supplement I., C., 1. Passage of dis- 
solved salts through a porous partition until equality of concentration is set up. 
Use in purifying beet-molasses. Semi-permeable membranes; law of osmotic 
pressure; comparison with Boyle’s Law for gases. Application to plant-cell. 
5. Revision of work of First Year, II., B., 2. Use of spring balance to 
measure a ‘force’ (i.e. a push or a pull) in terms of weight. Hooke’s Law in 
the stretching of strings, the bending of beams, &c. Use of a single (rough) 
fixed pulley; measurement of its ‘etticiency.’ Use of movable pulleys. The 
Principle of Work introduced for the determination of their efficiency. 
Loss of work by friction; simple laws of friction. 
Application of Principle of Work to lever, to haulage on an incline (without 
and with friction), &c. 
6. Conditions of equivalence of a single force (e.g. a pull in a cord) to two 
others. The vector law. Applications: the suspension bridge, cantilever 
frames, &c. 
D. Heat. 
1, Revision of First Year work. Mean temperatures in meteorology ; regu- 
larity of mean seasonal changes over long periods. Geographical isotherms, 
Temperatures at high altitudes and at great depths in sea. 
Dependence of boiling and freezing points on pressure; regelation, skating, 
snowballs. 
2. Hot-water circulation; convection. Function of radiators. Loss of tem- 
perature through conduction. Experiments on and illustrations of convection, 
radiation, and conduction: clothing, bark of trees, radiation from gravel and 
vegetation, &c.; thermostats, the thermos flask, temperature of ‘Tube’ rail- 
ways, &c. 
Curves of cooling of equal amounts of different substances (e.g. water and 
sand) ; geographical importance of slow rate of cooling and heating of water. 
Lagging of temperature at different depths below surface of soil. (To be 
taken in connection with I., B.) 
3. Extension of First Year, II., C., 3; separation of liquids by distillation. 
Applications : petroleum industry, turpentine and resin. 
Simple treatment of vapour pressure. 
Evaporation and condensation. Precipitation of rain and dew. Simple 
hygrometry ; determination of dew-point; relative humidity. Wet and dry 
bulb thermometer. 
Cold produced by evaporation. Ice-making, cold storage. 
