VOL. LXV."] PHILOSOPHICAL TRANSACTIONS. 715 



The extreme badness of the weather no less retarded the operations of the 

 survey than the celestial observations ; for there was almost constant rain, mist, 

 or high wind, to obstruct the use of the theodolite : indeed all the people of 

 the coimtry agreed, it was the worst season that had ever been known. So that 

 it was not till the 20th of October that the sections had been carried all round 

 the hill. Nor would this work, have been so much forwarded as it was, had it 

 not been for the use of an additional theodolite of the same construction, and by 

 the same maker, as the former, which was lent me, on my request, by the 

 right honourable James Stuart Mackenzie, lord privy seal for Scotland ; who, 

 having long cultivated a distinguished taste for astronomy, was pleased to honour 

 the experiment of attraction with every assistance which his interest or recom- 

 mendation could procure. I am particularly to acknowledge the favour he 

 conferred on me, by introducing me to the acquaintance of Sir Robert Menzies, 

 Baronet, his brother-in law, a gentleman conversant in mathematical and 

 philosophical learning, who honoured me with his friendship during my 

 residence in the country ; and, besides many personal civilities shown to myself, 

 rendered many material assistances to the main purpose of carrying on the 

 experiment. It is with pleasure also, that I acknowledge the civilities of all 

 the neighbouring gentlemen, who often paid me visits on the hill, and gave me 

 the fullest conviction that their country is with justice celebrated for its hospita- 

 lity and attention to strangers. I was honoured also by visits from many learned 

 gentlemen who came from a great distance ; particularly the lord privy seal. 

 Dr. Wilson, professor of astronomy at Glasgow, and his son, and Dr. Reid, 

 professor of moral philosophy, and Mr. Anderson, professor of natural philo- 

 sophy, also at Glasgow, Lord Polwarth, Mr. Ramsay, professor of natural 

 history at Edinburgh, Mr. Commissioner Menzies, of the customs at Edin- 

 burgh, Mr. Copland, and Mr. Playfair, of the university of Aberdeen, the 

 Rev. Mr. Brice, and my esteemed friend Col. Roy, who had been my com- 

 panion in the journey as far as Edinburgh. So great a noise had the attempt of 

 this uncommon experiment made in the country, and so many friends did it 

 meet with interested in the success of it ! 



The use of the 1 theodolites at once, as mentioned above, much forwarded 

 the completing of the sections all the month of October ; Mr. Menzies observ- 

 ing the bearings at one station with one theodolite, while Mr. Burrow observed 

 the altitudes or depressions with the other theodolite at the other station ; and 

 the labourer, who used to plant the poles in the hill, taking only one with him, 

 and fixing it up at one place to be observed at both theodolites, and then 

 removing it to the next station for the like purpose. Notwithstanding which, 

 the weather became at length so bad, by the early coming in of frost and snow 

 in the beginning of November, when the survey was nearly completed, as to 



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