326 Mr. Galbraith on the Figure of the Earth. 



the usual formula, which, from their proximity, cannot intro- 

 duce any considerable error, as none are selected for this pur- 

 pose whose latitude differs more than about 5° on each side of 

 it, from that to which they are reduced. As an equal number 

 was generally chosen on each side of it too, any small error 

 in the formula of reduction which was used, or Al = + 0*208 

 (sin 2 A" — sin 2 A'), will be by that means counteracted. 



No doubt objections may be urged against this mode of 

 procedure ; but it is perhaps the best under the present cir- 

 cumstances of the problem which can be employed, as the 

 most accurate method of distributing the observations regu- 

 larly over the quadrantal arc of the meridian. Now a series 

 of observations distributed regularly over the meridian is of 

 considerable importance to determine the exact ellipticity, even 

 when the method of the least squares is employed ; for in this 

 case also a preponderance of observations at any latitude has 

 its effect in obtaining the compression. — Having now assigned 

 the reasons for adopting the methods we have chosen, it re- 

 mains to apply them to a collection of all the experiments 

 which could with confidence be employed. These are prin- 

 cipally the series of Captain Kater, M. Biot, Captain Sabine, 

 M. Freycinet, M. Duperrey, together with a few more from 

 Sir Thomas Brisbane, Captain Hall, and perhaps one or two 

 others. 



Places. 



Rawak 



Sumatra 



St. Thomas 



Galapagos 



Maranham 



Ascension (D.) 

 Ascension (S.) 

 Sierra Leone... 



Trinidad 



Bahia 



Madras 



Guam 



Jamaica 



Isle of France.. 

 Isle of Mowi ... 



San Bias 



RioJaneiro(H.) 



Latitude. 



1' 



1 

 24 

 32 

 31 

 55 



7 .55 



8 29 

 10 38 



12 59 



13 4 

 13 27 

 17 56 

 20 9 



20 52 



21 32 



22 55 



34" S. 

 49 N 

 41 N. 

 19 N 

 43 S, 

 9 S, 

 48 S. 

 28 N, 

 56 N 



21 S. 

 9N 



51 N. 



7N 

 56 S. 



7N 

 24 N, 



22 S. 



Experi- 

 mental 

 Pendulum. 



39*01482 

 39-01812 

 39-02074 

 39-01717 

 39-01214 

 39-02364 

 39-02410 

 39-01624 

 39-01884 

 39-02223 

 39-02338 

 39-03023 

 39-03144 

 39-04769 

 39-04737 

 39*03828 

 39-04374 



Rio 



