PROCEEDINGS OF THE SECTIONS. 
a ee 
SECTION A. 
ASTRONOMY, MATHEMATICS, AND 
PHYSICS. 
PRESIDENTIAL ADDRESS. 
By R. W. Capmany, M.A., B.C.E., Adelaide. 
I wave selected as the subject of my address to you on this 
occasion, a matter which, if an encyclopedia were to be 
written dealing with the subjects set down for consideration 
by this section, would probably occupy but a very small 
amount of room in the book. It is, however, a subject 
which has considerable Jocal application; and in attempting 
something like a general review of the matter, I find that it 
is quite big enough to handle within the confined limits of a 
President’s‘address. I propose tc deal with 
TipaL THRORY AND SOME APPLICATIONS. 
Before the discovery of the laws of universal gravitation, 
the existence of a rational theory as to the cause of the tides 
- was out of the question, and ,we find accordingly that the 
theories in vogue up te the time of Newton may be desertbed 
ag both wild and varied. Thus Timzus ascribes them to 
the discharging of rivers into the sea. Aristotle, Hera- 
clides, and others considered that chey were due to winds 
set up by the sun or mooh, striking the water. Plato set 
them down as bodily oscillations of large bodies of water 
within the earth; whiist Apollonius, in common with many 
old Greek philosophers, regarding the earth as an animal, 
thought the tides were due to the earth’s breathing. This 
suggestion also occurs in Chinese writings. The close con- 
nection between the motions of the moon and the tides, 
especially in the North Atlantic, could not but impress the 
earlier thinkers on this subject; but most of them were, 
perforce, content to ascribe it to some occult quality on the 
part of the moon. Descartes applied his vortex theory of 
