Proceedings of the Royiih,^ft}tv>tion. 389 



great extent ; the ai-ea of one formed by 'Culsfibugh, Kijypurc, and 

 Keeper Mountains, is about 3800 sqtiare miles, or nearly -J of the 

 whole surface of Ireland; its spherical excess being nearly 50''. 

 Many of the sides are not less than from 80 to 90 miles, while some 

 of them extend upwards of 100 miles. These immense distandes 

 have generally been observed by the aid of plane mirrors reflecting 

 Ih^ solar iaj^s, a method which has proved of eminent service in the 

 triangulation of Ireland. It remains to add the necessary astrono- 

 mical observations for determining the latitudes of some of the prin- 

 cipal stations, as well as the direction of the meridian, and it would 

 contribute very especially to enhance the value and extend the uti- 

 lity of the work, if the difference of longitude between the extremities 

 of the kingdom, now connected by triangulation, were also determined 

 by signals. This may be considered with regard to an arc of longi- 

 tude, as analogous to determining the amplitude of a meridional 

 arc, and not only assigns the difference between the places where the 

 signals are observed, but furnishes the means of determining the 

 longitude of every other point connected by the triangulation, and 

 contributes to the detennination of the figure of the earth, more 

 especially that portion embraced by the triangulation in question. 

 ' 'We have great pleasure in adding that the geodetical operations 

 of India have of late received a fresh impulse ; the most perfect and 

 splendid instruments ever produced in this or any other country have 

 of late been sent out by the East India Company for this purpose ; 

 and further they have been consigned to hands, by whom, we be- 

 lieve and hope, they will be used with an energy and skill, worthy 



' ^iEfe liberality and munificence with which they have been provided.' 



" Such is an imperfect sketch of what is now doing by this country 



to advance this department of science ; and if we add to it the late 



' efiffablishment of observatories at the Cape and New South Wales, 



'it tnay be said with confidence, that the reproach too often justly 



- ''-%lade, can no longer be urged against the government, of indifference 

 'i't^ the objects of science, unless their immediate tendency be visible, 



'^fef ilictekie the political power, or advance the commercial interests 



''^^jNy^U^ry;-- -■■^- ■■; :....::...;..;..... i, • 



