Meteorological Observations at Hudson, Ohio. 267 
have added for comparison three years’ observations at Cam- 
bridge, and two years’ observations at Toronto. 
Hudson, . ; : 28:808 
Reduction for 1141 fet, : - 6h -22z2 
Correction for pa bd : . — 010 
Zero error, . ‘ + .007 
30-027 
Cambridge, : ‘ 29:940 
Reduction for 50 feat. ; ‘ +055 
Correction for gravity, ; OT 
29.988 
Toronto, : : 29608 
Hisduciion for 342 (et, : ; + 378 
Correction for gravity, . . 3 —-004 
Zero error, ‘ ; : — 004 
) 29-978. 
Comparing these results with those given in my former article, 
we have— 
Hudson, . , , p 30:027 
Cambridge, . ‘ . 29-988 
Toronto, . “ . , 29-978 
New York, ‘ ae . 29-977 
Montreal, . ‘ . ” 29-989 
Quebec, . , ; > aks pp G1e 
The excess of pressure at Hudson is remarkable, and indicates 
a probable error in the assumed elevation of the place. If we 
suppose the elevation to be 1092 feet, the resulting pressure will 
be 29-983. ‘This gives an error of 50 feet in the assumed eleva- 
tion of Hudson, which seems hardly admissible ; nevertheless 
that result (1141 feet) was derived from an imperfect connexion 
With a hasty rail-road survey from lake Erie. 
It has been justly remarked by Colonel Sabine, that the oscil- 
lations of the barometer are the complex effect of changes in the 
pressures of the vapor and of the gaseous atmosphere ; and that 
while we confine our attention to this complex effect, we fail to 
detect the causes of the phenomena. But as soon as we separate 
