SCIENCE IN SECONDARY SCHOOLS. 179 
carbon also unites with oxygen. Heating small quantities in oxygen and 
nitrogen will reveal the fact that no new gas is formed in the latter case, while 
it is formed abundantly in the former. A further confirmatory experiment may 
be made by the burning of magnesium in carbon dioxide. 
The candle can now be more thoroughly investigated, the decrease in volume 
of air demonstrated by burning it over water under a bell-jar, and the products 
of combustion found. This will naturally lead to the question—Is water an 
oxide? and its composition may be proved by the burning of magnesium 
powder in steam, with the formation of magnesium oxide and a new gas, 
hydrogen. 
A’ closely knit piece of work of this kind, in which fresh materials and 
facts are arbitrarily introduced by the teacher as little as possible, is of the 
utmost value. The girls may be lett very free to suggest and carry out their 
own experiments, the class being pulled together from time to time by dis- 
cussion, summarising of results, and formulation of fresh problems. Variety 
of method will enable different members of the class to make their own 
individual contributions to the discussion, and excellent practice in clear 
exposition may be given by allowing one member who has performed a par- 
ticularly useful experiment to demonstrate to the whole class and be questioned 
by the others. 
III. Ages 14 and 15.—As adolescence progresses the mind rapidly expands, 
and more or less consciously craves wide horizons and broad and generous 
views. Very simple astronomy, giving some idea of our present knowledge of 
the Universe and how it has been attained, may be made a most fruitful and 
stimulating study at this stage. While it must be in large part didactic, it can 
be taught in such a way that the pupils’ own observations, supplemented by 
diagrams and lantern slides, are used as the groundwork, and the gradual 
accumulation of observed fact and consequent modification of opinion can be 
appreciated. An historical treatment is at the same time both helpful to a 
clear understanding and very rich in human interest. 
The following practical work can easily be done by girls of this age, in 
a school situated in a district not too liable to fogs, if the work is begun 
in the autumn term. The observations must of necessity be made out of school 
and must constantly be discussed and checked in class. 
1. Identification of the chief constellations; observation of the fact that the 
fixed stars and constellations keep the same relative position but trace out a 
circle round the Pole Star complete in twenty-four hours; and that the whole 
scenery of the sky shifts its position as the seasons progress. 
2. Identification of such planets as may be visible; the keeping of careful 
charts to show the apparent movement of one which moves in a larger, and 
one which moves in a smaller, orbit than the earth. 
3. Observations on time of rising and setting, position of rising and setting, 
and path across sky of sun and moon. 
4. Phases of the moon. 
With a small telescope or even very good field-glasses the work can be 
greatly extended, the nebula in Orion which can just be detected by the naked 
eye can be found with certainty; the surface of the moon can be studied; the 
moons of Jupiter can be found, their movements observed; and the fact dis- 
covered that whereas the planets can be magnified to appear as discs, the fixed 
stars cannot. 
It is important that the observational work should get well ahead of the 
lessons which deal with its interpretation, and there is no difficulty in this 
as at first a good deal of help will have to be given in suggesting points for 
observation, in criticism of charts, and so forth. Early ideas with regard to 
the earth, sun, and stars may be described, and possible interpretations of the 
girls’ own observations of the apparent movements of the fixed stars and 
of the sun discussed. It is important that, at the outset, they should fealise 
the possibility of the movement being regarded as either real or only apparent, 
and what the acceptance of either theory would involve. They are then pre- 
pared to follow with zest the interpretations given by Ptolemy, Kepler and 
Copernicus, to sympathise with those who still doubted the real movement of 
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