460 H. A. Hazen—Reduction of Air-pressure to Sea-level. 
TABLE V.—Valdobbia above Alessandria. 
Month. | Laplace. | Pilference || angot. | Piference |] Hazen (2. | Diorenes 
January 7699’ — 98’ 7904’ +51’ 78637 — 6’ 
February T7196 — 1 7904 +51 7916 +47 
March 7823 +26 7904 +51 W911 +42 
April 7811 +14 7835 —18 7887 +18 
May 7848 +51 7851 —2 7887 +18 
June 823 +26 7792 —61 7844 —25 
1 7842 +45 7818 —35 7854 —15 
848 +51 7822 —31 7860 — 9 
September 7827 +30 7861 + 8 7860 9 
7801 + 4 7854 + 1 1847 —22 
November 7735 —62 7828 —25 7830 —39 
b 7709 —88 7858 + 5 7862 7 
ear 7808 7851 7862 
Mean of months TT97 7853 7869 
The following formule are added : 
Mount Washington and Boge C= “ae *82 —0"'12 (30” —p) 
‘012 (¢— 
Professor Whitney has made Say tines years’ observations 
at Sacramento and Summit, California, stations 77 miles apart 
with a he of altitude of 6989’. The formula at these 
stations is O = 5/24 + 0’-25 (30’— p) — 0-010 (t—82°), the 
reversal of the ms n in ur ase term from minus to plus 
has been already noticed in the May number, page 366. 
It has been shown, then : 
Ist. The formula of Laplace gives too small results at high 
ake and low temperatures and too great at low pressures 
and oth temperatures. 
he pressure term is more liable to variation than the 
vmperatare term 
t is possible to so arrange the formula of Laplace as to 
separate the terms, and dispense with the use of logarithms. 
4th. It is possible to construct a formula from the actual 
Gem high shall give satisfactory results. 
wing paragraphs have been taken from an article in 
e 
“ Seay tor April 14th, 1881 (just received), on Periodic Oscil- 
lations of Barometric Pressure, by J. Arian Brown, F.R.S., 
(now deceas ed). They are of interest as Sasening some of the 
views amrancen | in the alia paper 
Sedgwick has said ae To explain difficulties in these mnpations 5 ieageem to 
pressure and tneipersiats ture) ‘the Paging strata have been shuffl accord- 
“Tf we suppose that the sitevodlon of gravity is not the only attraction which 
ai the pressure of the sphere, t this pressure varies through some 
o ting force such as an electric attraction of th nding upon the 
arying humidity of the air and pending its tem ture ; he 
exist i 
mployed, It is quite certain that many “oaewsrert will heotege: 
0 
edmit the “idea ar an alectiis attraction on our atmosphere in the present 
: 
75 
