ON SCIENCE IN SCHOOL CERTIFICATE EXAMINATIONS. 503 



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 producta 

 of combustion fouiud. This will naturally lead to the question— Is water an 

 oxide? and its composition may be proved by the burning of magnesium 

 powder in eteam, with the formation of magnesium oxide and a now gas, 

 hydrogen. 



A closely knit piece of work of this kind, in which fresh materials and 

 fact« are arbitrarily introduced by the teacher as little as possible, is of the 

 utmost value. The girls may be left 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 b»gun 

 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 

 a? 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 realise 

 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 

 the earth, and to be thrilled at the discovery of the parallax of some of the 

 fixed stars. The scope of the course must vary greatly with the ability of the 

 class and with its mathematical knowledge, but it must not only deal with the 

 solar system, but give an idea of the magnitude of the Universe as a whole. 



