6t4 PHILOSOPHICAL TRANSACTIONS. [aNNO 17Q5. 



eminently distinguished, from the asra of his reign, for his liberal patronage of 

 the arts and sciences. By his Majesty's command, the memoir was put into the 

 hands of Sir Joseph Banks, p. r. s. accompanied with such marks of royal muni- 

 ficence, as speedily obtained all the valuable instruments and apparatus necessary 

 for carrying the design into immediate execution. General Roy, to whose care 

 the conduct of this important business was committed, lived to go through the 

 several operations pointed out in the memoir, the particulars of which have been 

 detailed at great length in the Philos. Trans, where they will remain a testimony 

 of his zeal and ability in conducting so arduous an undertaking at an advanced 

 period of life. The further prosecution of the survey of the island, to which the 

 operations hitherto performed might be deemed only as subservient or intro- 

 ductory, seemed to expire with the General. 



The liberal assistance which his Grace the Duke of Richmond had on all oc- 

 casions given to this undertaking; and particularly the essential services per- 

 formed by Captain Fiddes, and Lieutenant Bryce, of the corps of royal engi- 

 neers, in the survey and measurement of the base of verification on Romney 

 Marsh, are acknowledged by General Roy in the strongest terms. A consider- 

 able time had elapsed since the General's decease without any apparent intention 

 of renewing the business, when a casual opportunity presented itself to the 

 Duke of Richmond of purchasing a very fine instrument, the workmanship of 

 Mr. Ramsden, of similar construction to that which was used by General Roy, 

 but with some improvements; also 2 new steel chains of 100 feet each, made 

 by the same incomparable artist. Circumstances thus concurring to promote 

 the further execution of a design of such great utility, as well as honour, to the 

 nation, his Grace, with his Majesty's approbation, immediately gave directions 

 to prepare all the necessary apparatus for the purpose; which was accordingly 

 provided in the most ample manner. 



Before entering on the ensuing account, it may not perhaps be improper to 

 enumerate some preliminary matters relative to the subject. The first mode of 

 mensuration adopted by General Roy, was that with deal rods, which had also 

 been used and approved of in other countries. In the course of the measure- 

 ment however it appeared, that the sudden and irregular changes which these 

 rods were liable to, from dryness, humidity, or other causes, rendered them to- 

 tally unfit for ascertaining the length of the base with that degree of precision, 

 of which it was at first thought they were capable. On this account they were 

 laid aside, and glass rods substituted in their stead. These rods were contrived 

 with great ingenuity to answer the purpose, as fully appears by the account given 

 of them in the Philos. Trans. But this mode of mensuration being the first of 

 the kind, seemed to require some proof of its accuracy, which consideration in- 

 duced General Roy to make a comparison between the glass rods and the steel 



