VOL. LXXV.] * PHILOSOPHICAL TKANSACTIONS. 23 



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the purpose for which it was originally intended; yet having been carried on with 

 instruments of the common, or even inferior kind, and the sum annually allowed 

 for it being inadequate to the execution of so great a design in the best manner, 

 it is rather to be considered as a magnificent military sketch, than a very accu- 

 rate map of a country. It would however have been completed, and doubtless 

 many of its imperfections remedied; but the breaking out of the war of 1755 

 prevented both, by furnishing service of other kinds for those who had been 

 employed on it. On the conclusion of the peaee of 1763, it came for the first 

 time under the consideration of government, to make a general survey of the 

 whole island at the public cost. Towards the execution of this work, the direc- 

 tion of which was to have been committed to our author, the map of Scotland 

 was to have been made subservient, by extending the great triangles quite to the 

 northern extremity of the island, and filling them in from the original map. 

 Thus that imperfect work would have been effectually completed, and the nation 

 would have reaped the benefit of what had been already done, at a very mode- 

 rate extra-expence. 



Certain causes however prevented any progress being made in the work for 12 

 years longer, previous to the nation's being unfortunately involved in the Ame- 

 rican war;' it was therefore obvious that peace must be once more restored before 

 any new effort could be made for that purpose. The peace of 1783 being con- 

 cluded, and official business having detained Gen. R. in or near town during the 

 whole of that summer, he embraced the opportunity, for his own private amuse- 

 ment, to measure a base of 7744.3 feet, across the fields between the Jew's 

 Harp, near Marybone, and Black-lane, near Pancras; as a foundation for a series 

 of triangles, carried on at the same time, for determining the relative situations 

 of the most remarkable steeples, and other places, in and about the capital, with 

 regard to each other, and the Royal Observatory at Greenwich. The principal 

 object he had here in view (besides that it might possibly serve as a hint to the 

 public, for the revival of the now almost forgotten scheme of 17^3) was, to faci- 

 litate the comparison of the observations, made by the lovers of astronomy, 

 within the limits of the projected survey; namely, Richmond and Harrow on 

 the west; and Shooter's-hill and Wansted on the east; when very unexpectedly 

 he found that an operation of the same nature, but much more important in its 

 object, was really in agitation. 



In the beginning of October, 1783, Comte D'Adhemar, the French ambas- 

 sador, transmitted to Mr. Fox, then one of his Majesty's principal secretaries of 

 state, a memoir of M. Cassini de Thury, in which he set forth the great advan- 

 tage that would accrue to astronomy, by carrying a series of triangles from the 

 neighbourhood of London to Dover, there to be connected with those already 

 executed in France, by which combined operations the relative situations of the 



