434 
KANSAS CITY REVIEW OE SCIENCE. 
In this law we come upon square of distance, but in Kepler's we found 
square of time ; let us see if there is any relation. 
It is proven in the higher analysis, that spheres attract matter that is upon 
their surfaces with a force that can be found by dividing the mass of the sphere 
by the square of the radius. It follows from this, that the intensity of attraction 
of a sphere at at any distance from it can be determined by dividing gravity on 
its surface by the square of the desired distance. This is simply another way of 
stating the law of gravity as given above. Now, the force of gravity exerted upon 
the earth by the mass of the Sun is equal to i, how great is it at Mercury? The 
distance of Mercury from the Sun is .3872 whose square is . 15022384; whence i 
divided by .15022384 equals 6.66; therefore solar gravity exerted on Mercury is 
6.66 times stronger than on the earth. In this method, we divided gravity at 
the earih's distance by the square of Mercury's distance, that is : we made use of 
square of space ; but singularly enough, the same result can be reached by using 
square of time. Thus, if we divide Mercury's distance from the Sun, by the 
square of its periodic time, we will have .3872 divided by .058039=6.66 as 
before. 
The law of gravity might be given in this manner : the attraction of the Sun 
on each planet is equal to its distance divided by the cube of its distance. Thus : 
— the distance of Jupiter from the Sun is 5.2016 whose cube is 140.7; and 5.2016 
divided by 140. 7=.o37229, which is the intensity of gravity exerted on Jupiter 
by the Sun, that on the earth being i. But we have arrived at the same point 
whence we started at the beginning of this note, because, since 140.7 is the cube 
of the distance of Jupiter, it is also by the law, — the square of the time of its 
revolution. Here is a table of intensities of solar attraction exerted on all 
the planets, found by dividing their mean distances by the squares of periodic 
times, instead of the usual way of dividing gravity on the Sun's surface by squares 
of planetary distances. We made use of time in place of space. The first column- 
gives the mean distances of planets ; the second, the squares of their periodic 
times, and the third, — quotients of the first divided by the second, which are the 
intensities of solar attraction, light and heat, on all the planets, and also the 
centrifugal tendencies developed by planetary motions. 
Names of 
Planets. 
Mercury . 
Venus . . 
The Earth 
Mars . . 
Jupiter . . 
Saturn . . 
Uranus . 
Neptune . 
TABLE III. 
Solar Gravity 
Distances Squares of Heat and Light, 
of _ ttiei£ and Centrifugal 
Planets. 
.3872 
.7233322-^ 
. 1.5238 
. 5.2016 
• 9-5371 
. 19. 182 
. 30.036 
Periodic Times. Tendencies." 
058039=6.66 
378458=1.9135 
53748 = .4306 
7 = -037229 
516 = .0109737 
4311 = .0027177 
= .001108 
I 
3 
140 
■ 867 
7058 
270* " 
