Physics and Chemistry. 411 
_ The calculated time for the above observed means differs less than 20” 
om the actual time. 
Observed Means, 498625 *864625 1:000000 
Theoret. Diff. of Time, 59/ 48/’ 119/ 40/” 180’ 
Observed “ “ “ DOL 0 120 0" 180’ 
The varying centrifugal force to which the earth is subjected by the 
ipticity of its orbit, rust, in like manner, produce annual tides. The 
disturbing elements render it impossible to determine the average monthly 
height of the barometer, with any degree of accuracy, from any observa- 
tions that have hitherto been made. We may, however, make an inter- 
esting approximation to the annual range, still using the St. Helena rec- 
ords, which are the most complete that have yet been published for any 
station near the equator. Comparing the mean daily range, as determined 
by the average of the observations at each hour, with the mean yearly 
i as determined by the monthly averages, we obtain the following 
Fesuits 
Daily Annual Approximate 
Year. range. range. Ratio. Solar distance, 
1844 0672 in. "1650 in. 24553 137,070,000 m. 
1845 0646 “ 1214 “ 18793 80,300,000 “ 
1846 0670 « 1214 * 1°8120 74,650,000 “ 
8)-1988 3)4078 3)6°1466 
0668 “1359 2-489 95,446,000 “ 
Mean 0663 -1290 1-9457 86,056,000 “ 
2)1326 2)-2649 2)8-9946 
0663 90,702,000 “ 
1324 
The approximate estimates of the solar distance are based on the fol- 
lowing hypothesis : 
0 A==area described by radius vector in time ¢. 
Let ¢', a’, r’, a’, represent corresponding elements of the annual revo- 
lution, “Then? 
Ayal ters Set as 
But the forces of rotation and revolution are so connected, that a 
liffers but slightly from a’. 
e2:e'2:irir 
rf fi oe e'?r very nearly. 
=a 
_ It may be interesting to observe how nearly r (22,738,900 m.) corres- 
‘Ponds with Kirkwood’s value of + (24,082,000 m.), A more thorough 
‘omprehension of all the various effects of gravity and rotation on the 
Rmiy ere, would probably lead to modifications of our formule that 
ould show a still closer correspondence. 
