i88i.] Geology as a Science and an Art. 449 
describe a circle during one rotation. The zenith of other 
localities would describe ellipses, which ellipses would show 
a greater difference between the major and minor axis the 
nearer they approached the Equator, until at or near the 
Equator the zenith would trace a straight line, equal in 
length to the major axis of the ellipse. 
As, however, the axis of the earth changes its direction 
annually, to the amount of about 2o''*25, towards or nearly 
towards the first point of Aries, the circle becomes a curve, 
which I have named the Nautilus curve. If it be a fadt 
that the position of the centre of gravity of the Earth pro- 
duces the apparent changes in the zenith distance of the 
stars, it will be possible, by aid of this Nautilus curve, to 
measure the amount of change in declination of any star 
near the poles, and also to show where the right ascension 
of any star will change, and how this change will vary 
during each month of the year. Such a demonstration 
must, I think, carry with it a proof of its accuracy. 
(To be continued.) 
II. GEOLOGY AS A SCIENCE AND AN ART* 
By C. Lloyd Morgan. 
§ F the several questions which my subjedl involves I 
give precedence to the very general one, “ What is 
Science ?” Now-a-days we hear noj: a little of 
science, of scientific culture, and of scientific dis- 
coveries. But I have no doubt that, if we were to ask a 
number of people of average education to set down a defini- 
tion of science, many of them would be puzzled what point 
or points to pick out, by which to distinguish scientific 
knowledge from other kinds of knowledge. And I think that 
not a few of them might be driven to writing down a list of 
the several branches of science, and stating that science has 
to do with chemistry, geology, natural history, metallurgy, 
&c., &c. That is to say, they would define science by its 
subjedl matter. But we hear now-a-days of the science of 
history, the science of language, even the science of religion, 
while the science of sociology claims as its domain all the 
* Read before the South African Philosophical Society in Cape Town. 
