r . 
pi 
a A sei 
; a 
. t % @ 
-"* ss. W. Meech on the Sun’s Daily Intensity. 49 
.. dications of an unquestionable standard, but this was not attain- 
able. One common source of error, however, in the observations 
two or more persons, and in no instance, where there was a dif- 
Bk: ference of opinion, was the observation recorded. Still, it is pos- 
_ sible that the conclusions arrived at may in some instances be in- 
accurate ; for I found that when observations were made by two 
' persons on the same thermometer, they often differed from each 
other as much as a degree, and there is reason for supposing that 
even when alike they might be erroneous. I have dwelt upon 
the possibility of error from the imperfection of both thermome- 
ters and observers, because from the mode of experimenting 
adopted, a slight difference between the actual heat evolved and 
that observed, would present a very considerable difference in the 
proportion in the air itself. . 
The want of a barometer prevented any modifications in the 
| eHealation’ of results, on account of variations in the density of 
| the air 
ae 
(To be continued.) 
= 
Art. VIL—On the Computation of the Sun's Daily Intensity 
at the exterior surface of the Eurth, and Secular Changes of 
Heat; by L. W. Mercu, A.B., Preston, Ct. 
_ Tuer are reasons for believing that the phenomena of solar 
heat may be as completely interpreted by analysis as are the tides 
Of the ocean. The subjoined contribution is offered in pursuance 
of this object. 
__ - Before proceeding to the general investigation, Jet it be pro- 
decrease of the eccentricity of the earth’s orbit: in conse- 
quence of which, the orbit approaches to the form of a circle, 
and the earth is constantly removing to a greater distance from 
f the sun, between the apses; the transverse axis remaining inva- 
niable. Let then e represent the eccentricity, regarded as con- 
Stant for one year; 9, the radius-vector; 7, the mean anomaly ; 
and 6, the true anomaly, for any given time. Also it is known 
that 4/1 —¢2 expresses the whole area of the ellipse ; and f30°d4, 
that of the elliptic sector corresponding to 6. Whence by Kep- 
TS law of equal areas, 
[ an/1—e? : f5092d0:: 24:9, or 
| ‘a0 
 dgn/1—e? 
; ¢. 
Srcoxn Senres, Vol. X, No. 28.—July, 1850. 1 
