in the trigonometrical survey of Great Britain. 77 
In Vol. 1, p. 173, Colonel Mudge gives 91* for its height, 
which differs only by half a foot. 
But at page 266 it is stated to be 118 feet, being 27 feet 
above the proper height. Again in Vol. 3, p. 307, it is stated 
to be 132 feet, or 41^ too high. 
The grounds of my assumption of 402 feet being the height 
of the Grand Junction Canal summit, near Tring, are these : 
The range of tide, from low water spring tides at sea, to 
high water near Somerset House, I presume to estimate 193- 
feet ; from this point to the Regent's Canal summit will be 
found 83 £ feet ; from this level I apply the revised section of 
the Grand Junction Canal = 299-f to the summit near Tring, 
making together 402 feet as above. 
From these levels it will appear, that Wendover Station 
above Brickhill is 861 — 571J- == 289T Colonel Mudge’s 
numbers give - - 905 — 683 — 222 
677 error. 
Arbury above Brickhill 7404 — 571-!-= 69 
Colonel Mudge - - 804 — 683 =121 
Error 52 
Wendover above Arbury 861 — 7407 = 1201- 
Colonel Mudge - - 905 — 804 =101 
Error 1 9-f 
Some fresh observations with the zenith sector made at 
Blenheim, and Sutton, would offer a fine check to the latitude 
of Arbury ; and also at Highbeach, and Botley Hill, a check 
to the latitude of Greenwich would be readily obtained. 
B. Bevan. 
Leighton, Bedfordshire, 
February, 1822. 
