wight, and freed from the erroneous assumptions now 
current as to their cause and immediate and ultimate results, 
it will be seen to give such changes of the periods of high 
noon in both hemispheres, as must necessitate new computa- 
tions for the guidance of mariners to ascertain latitudes, and 
afterwards the longitudes of their positions at sea. Presently, 
longitudes are computed by chronometer time from definite 
initial points, the sites of European Observatories. At first 
sight, it appears easy to define meridians of longitude east or 
west of these sites, calculating 15 degrees for each hour of 
the difference of the local time of high noon with that of the 
initial point selected. But if the action of the phenomena of 
the Precession of the Equinoxes, — that is the operation of 
terrestrial causes, in tilting the Earth upon the plane of the 
Ecliptic, and thus constantly altering the relative position of 
Points upon the Earth's surface with reference to the Sun — 
is to hasten the time of high noon in the northern hemi- 
sphere and retard it in the south, by ever so small an annual 
fraction of time, the result is a progressing variation in 
position of latitudes and longitudes, as previously defined, 
so that as there will be a continuously minute retardation of 
the time of high noon in the Southern hemisphere, there 
must be an apparent corresponding diminution of longitude.* 
Hence, the eastern boundary of the province of South Aus- 
tralia will be found at each adjustment of it (if continued as 
the 141st degree of East longitude) to overlap in an increasing 
amount its previously defined limits, and extend into Victoria. 
The writer submitted this view of the question several years 
ago, and now the re-adjustment of the boundary being called 
for, the actual facts corroborate the accuracy of his prognos- 
tications, and demonstrate necessity for a fixed line of 
demarcation. At same time, no question can vie in impor- 
tance with one so absolutely bound up with precautionary 
measures for ensuring the safety of mariners throughout the 
world ; and no time or expense should be spared in its 
thorough investigation, and in the computation and publica- 
tion of data, whereby apparent variations in position of pre- 
viously defined points in latitudes and longitudes, such as 
islands, reefs, shoals, &c, maybe ascertained by the mariner, 
and the causes of arjparent discrepancy of observations taken 
now, as compared with previoxis ones, duly accounted for. 
The use in the present day by Science of the coffer in the 
Great Pyramid for the purpose I submit as its original design, 
and renewals of the experiment at successive periods of years, 
* That is, the defined site on the 141° east longitude, will in after 
observations be in longitude 140* so many minutes. 
