66 
ARCHDEACON PRATT ON THE ATTRACTION OF THE 
or, if a be expressed in degrees, =^(1 + 0-000073 (8.) 
This formula, as will appear in the issue, may be used for all values of a up to 38° 
without sensible error. 
25, Let «!, a. 2 , .... ‘Ps be the successive values of a and p for the 
several compartments of a lime. Then these are connected by the equations 
0J2=0Ji+®i, a3=a2 + ?’25 
As the hills do not begin to rise north and north-east of the station Kaliana till be- 
tween a distance of three-quarters and a whole degree, I shall assume* the first value 
of a (viz. a,)=0°-75. 
* If we wish to apply this method of calculation to any other particular case, we may make any other assump- 
tion we please regarding the first value of a, so long as we take care not to apply the method to calculate the 
attraction on a station too near to elevated ground. In short, we must see that the angle w in art. 14. is suffi- 
ciently small to be neglected in the formula therein deduced. If it be not, w'e must calculate the attraction of 
the nearer masses by a direct method. 
We may use the formula (8.) we have just deduced to calculate the values of a and <j> nearer to A than a,. 
In this way we shall obtain the following series of values, writing them backward from a, towards A. 
o o 
=0'6818 
09 =0-06818 
a_ j=0-6198 
(p- j=0-06198 
a_ 2=0'5635 
<p- 2=0-05635 
a_ 3=0'5122 
0_ 3=0-05122 
a_ 4=0-4657 
0_ 4=0-04657 
a_ 5=0-4234 
0_ 5=0-04234 
a- g=0-3849 
0_ g=0-03849 
a_ 7=0-3599 
0_ 7=0 03599 
a_ 3=0-3181 
0- 8=0-03181 
a_ 9=0-2892 
0_ 9=0-02892 
a_j9=0-2629 
0_in=O-O2629 
a_jj=0-2390 
0_ji=O-O239O 
a_j2=0-2172 
0_j2=O-O2172 
a_i3=0-1975 
0_j3=O-O1975 
a_j4=0-1795 
0_14=O-O1795 
a_j5=0-1632 
0_j5=O-O1632 
a_je=0-1484 
0_,g=O-O1484 
a_i7=0-1349 
0_j7=O-O1349 
&c. 
&c. 
