164 REPORTS ON THE STATE OF SCIENCE.—1917. 
developed plant continues to respire. Reference to behaviour of water-plants 
(First Year, I., C., 2 (d)) leads to discovery that they emit oxygen. Distinction 
between respiration and assimilation of carbon dioxide. Experimental dis- 
covery (i) that both processes occur in plants growing in air, (ii) that oxygen is 
necessary to plant life, (iii) that breathing proceeds in light and darkness, in 
cold and warmth. 
2. Assimilation of carbon dioxide by plants; importance in general life- 
economy. Plant substances built up mainly of carbon, hydrogen, oxygen, and 
nitrogen. The leaf the organ of assimilation of carbon; microscopic differences 
between leaves according as carbon dioxide is supplied or withheld; starch 
grains, the iodine test. Starch shown to contain carbon. Manufacture of 
starch. Relation of starch to other substances in plants. Experiments on rela- 
tion of light and darkness, cold and warmth, to assimilation; also of seedling 
leaves, green leaves, and variegated leaves. 
3. Assimilation of carbon dioxide as feeding. Comparison of food-processes 
in plants and animals. Dependence of animal life on activity of the green plant. 
II. Physical Section. 
A. Astronomy. 
Observations and discussions to lead up to the explanation of the (apparent) 
annual motion of the sun. The work to be conducted as in the First Year. 
1. Revision of, and exercises upon, First Year’s work—including the problem 
of graduating a horizontal sun-dial. (Dials for permanent use may be made in 
the handwork class, also simple altitude-meters for home observations.) 
2. The moon. The class to make a collection of drawings of the phases 
preparatory to explanation by means of a simple model. The moon observed to 
move among the stars. Rough measurement of interval between southings. 
Conception of ‘mean lunar day.’ (Compare with First Year, II., A., 1. A 
clock may be regulated to keep ‘mean lunar time.’) Lunar and calendar 
months. Note that at the same ‘lunar time’ on different dates the constellations 
cccupy a series of different positions, repeated each month. 
3. Completion of the record begun in First Year, II., A., 5 (b). At the 
same ‘ solar time’ the constellations occupy a series of positions repeated each 
year. Comparison with results in § 2 brings out that the sun moves among the 
stars. 
4. Continuation of First Year record, II., A., 5 (a). Graph of a year’s 
observations to be drawn and compared with similar graphs of former years. 
A horizontal line across graph represents the sun’s mean altitude at noon and 
divides the curve into two balancing segments. The sun spends half the year 
above and half below this line (the ‘celestial equator’). The equator cor- 
responds to the plane of the sun-dial used in First Year, II., A., 4. Compila- 
tion of a table of the sun’s ‘declination’ from the graph. Use of this table 
in determining latitude at sea. 
Representation of the curve ona cylindrical projection (see footnote to First 
Year, II., A., 2), the equator being taken as datum-line. The paper above the 
curve is cut away and the residue bent into a cylinder. The (apparent) annual 
path of the sun among the stars is then seen to be a plane (the ‘ ecliptic’) 
inclined at 234° to the plane of the equator. Explanation of the seasons. 
5. Revision and summary of the two years’ work. Distinction between the 
‘solar,’ ‘ lunar,’ and ‘ sidereal’ days. Explanation in terms of (i) a diurnal 
rotation of the earth about its axis, (ii) an annual revolution of the earth about 
me oe (iii) a monthly revolution of the moon about the earth. The Gregorian 
calendar. 
B. Geology. 
Field-work arranged as part of the course in biology or geography should 
include observations of the stratigraphical disposition of different types of 
earth and rock (e.g. of the sand and clay on Hampstead Heath in London), 
and of the relations thereto of the surface features (including the outflow 
of streams). The nature and effects of river action should also be studied unless 
taken in a previous year. 
