618 ON THE FIGURE, DIMENSIONS, AND MEAN SPECIFIC GRAVITY OF THE EARTH, 
Liverpool Observatory, the other a temporary observatory erected at Kingstown. 
The following Table contains the comparison of the astronomical and geodetical 
determinations : — 
Stations. 
Observed 
Geodetic Longitude. 
Difference. 
Longitude W. 
Spheroid (A). 
Spheroid (B). 
(A). 
(B). 
Liverpool 
m s 
12 0*05 
m s 
12 0-35 
m s 
12 0-26 
-I-0-30 
-I-0-21 
Kingstown 
24 31-20 
24 31-48 
24 31-26 
-hO-28 
-hO-06 
Feaghmaan 
41 23-23 
41 23-02 
41 22-74 
— 0-21 
-0-49 
Observatories. 
The positions of the principal observatories, as calculated by their connexion with 
the Triangulation of the Ordnance Survey, are contained in the following Table; — 
Names. 
Latitudes 
Longitudes 
On Spheroid (B). 
As observed. 
Diff. 
On Spheroid (B). 
As observed. 
Diff. 
O / // 
O 4 U 
m s 
m s 
s 
Greenwich 
51 28 39-70 
51 28 38-30 
+ i-40 
0 0-00 
0 0-00 
0-00 
Edinburgh 
55 57 17*57 
55 57 23-20 
— 5-63 
12 43-61 
12 43-00 
+ 0-61 
Dublin 
53 23 14-21 
53 23 13-46 
+ 0-75 
25 20-87 
25 22-00 
-1-13 
Cambridge 
52 12 51-90 
52 12 51-63 
+ 0-27 
0 23-26 
0 22-69 
+ 0-57 
Oxford 
51 45 38-56 
51 45 36-00 
+ 2-56 
5 2-91 
5 2-60 
+ 0-31 
Durham 
54 46 5-27 
54 46 6-20 
-0-93 
6 20-25 
6 19*75 
+ 0-50 
Liverpool 
53 24 47-06 
53 24 47-80 
-0-74 
12 0-26 
12 0-05 
+ 0-21 
Makerstown 
55 49 1-83 
55 49 6-00 
—4-17 
19 26-20 
19 28-00 
-1-80 
Armagh 
54 21 10-76 
54 21 12-67 
-1-91 
26 35-52 
26 35-50 
+ 0-02 
Figure of the Earth. 
In obtaining the spheroid most nearly representing the measured arcs of meridian, 
we shall follow the method given by Bessel in his determination of the figure of the 
earth in Nos. 333 and 438 of the ‘ Astronomische Nachrichten substituting for the 
English arc as used by him, the data of the present results, and for the Indian arc 
as used by him, the data contained at page 427 of Colonel Everest’s ‘Account of 
the Measurement of Two Sections of the Meridional Arc of India.’ 
Colonel Everest’s measurements are expressed in terms of his standard 10- foot 
iron bar A, and the standard 6-inch scale A, twenty parts of any linear result being 
in terms of feet of the iron standard and one part in terms of feet of the 6-inch scale. 
By means of the comparisons contained at page 436 of Colonel Everest’s work and 
at pages 101 and [40] of the ‘Account of the Measurement of the Lough Foyle Base,’ 
it will be found, that to reduce the results contained in the former work to feet of Oj, 
they must be multiplied by *99999026. There is, however, some uncertainty in the 
unit of measure of the earlier portion of the second East Indian Arc. 
Peruvian Arc . — The data are a mean between the reduced results obtained by 
Delambre and Zach (Base du Syst. Metr. iii. 133, and Mon. Corresp. xxvi. 52). 
