A, Hinrichs on the Density, Rotation, and Age of the Planets. 41 
where the unit of a is arbitrary and that of ¢ and 4 may be as- 
sumed if the unit of is determined in conformity therewith. 
We then may take for our earth a=100, e=10, A=1; then the 
unit of # will be known as soon as the amount of resistance oF 
the density of the ether is given, Neither being exactly known 
e must be satisfied with an estimate; and thus (12) easi ly 
bore that if our eurth approaches the sun annually by ten feet, 
unit of age t is ten thousand millions of years. 
It will be seen that, ve ie as the st egonare of our 
earth is known, the unit of # will be determ 
By means of (10’) or its reaesabink (12) a. ain now enabled 
to calculate the effect of resistance on the ania of fe cay 
at any age #, both in future (+4) and the past (— e now 
to a comparison of the results of this eas with ob- 
servation, using the following data’ 
a 9 ray 
gh 
Mercury, 38 3-9 1:23 2 
Venus 72 9°98 1:07 1 
: 100 10:00 1:00 1 
152 514 9 
Aste 10°0 (assumed.) 
Jupiter 520 1144 24 
rn, 954 94°8 14 08 
Uranus, 1918 45°8 18 
<a 3004 42:5 23 
Past. Present. Future. 
9g 1 
4 2 0 4 6 
Mercury, 240 95 38 15 6 2 
Venus, 181 100 72 45 29 18 
252 159 100 63 40 25 
Mars, 955 381 152 65 9 
Jupiter, 125 626 520. «488~=<“‘z C8 
1991 1378 954 are 
Uranus, 6351 3490 1918 1078 593 
Neptune, 5985 4237 3004 2127 1504 1066 
For an asteroid ie which eal, 
2 0-0 5 1-0 
Distance, ine 770 280 28 3 
* For G=95,000,000 X 528, or about 50,000,000,000 ten-feets, hence a—2== 
49,999, 999,999 ten-feets ; consequently by (12) 
Wis « ate ee 1,9 1 year; 
menind =a10 log -— < 0:0000000001, > being 1 year; 
si iv 119; meant Tee eae by Babinet, 
