ManrEN— Comparative Atmospheric Pressure. 217 
observations can be carried ; while a rapid barometric rise, and an influx of 
moist air also, are frequently coincident. The misapprehension obviously 
arose from the general acceptance of the theory that the lower pressure of 
the Southern Hemisphere, as compared with the Northern, is due to the 
larger relative area of ocean in the former, But that the presence of aqueous 
vapour is not the only, or even the chief source of deficient pressure, can be 
proved beyond dispute. Comparison of barometric readings after the sub- 
traction of the vapour tension will show this plainly. A very cogent 
illustration, however, is afforded by the tables already quoted, which show 
the pressure to be 29:932 at Hokitika, and only 29:871 at Christchurch, or 
‘061 in favor of the West Coast, notwithstanding that the latter has a mean 
humidity of ‘86, as compared with -77 at Christchurch, which, moreover, 
is to leeward of Hokitika as regards the prevailing wind. Hence the atmos- 
pheric pressure seems actually to diminish instead of increasing as the air 
loses its moisture. The truth appears to be that the atmosphere is subject 
to disturbances more or less analogous to those of the ocean—waves, cur- 
rents, eddies, and even tides, produced by causes and governed by laws as 
yet only imperfectly understood, but wholly irrespective of excess or deficiency 
of aqueous vapour, whose presence or absence probably is oftener the effect 
than the cause. 
17. There are many other climatological characteristics of New Zealand 
related directly or indirectly to the subject of Dr. Newman’s able essay, and 
I purpose treating of them on a future occasion. In the present paper I 
have simply endeavoured to prove—and I trust I have succeeded in the 
attempt—that whether Dr. Newman’s speculations as to the probable 
degeneration of the English race in New Zealand be well founded or not— 
for the sake of our adopted country we must hope the latter—at any rate 
deficient atmospheric pressure does not enter as a factor into the problem, 
Art. XVIII.—On the Longitude of Wellington Observatory. 
By Ven. Arcupgacon Srock, B.A. 
[Read before the Wellington Philosophical Society, December 9th, 1876.] 
A srr account of the establishment of a longitude for the Wellington 
Observatory will be found, it is hoped, interesting for the present meeting 
of the Society, and as a record for future reference. 
Some twenty-five years ago, H.M. ships ** Pandora" and “ Acheron” 
came to Australia for the express purpose, amongst other duties, of fixing 
the longitudes of different points in New Zealand, both ships being well 
provided with chronometers of the best construction. 
Bl 
