c 7s j 
VIII. Observations on the heights of places in the Trigonometrical 
Survey of Great Brit am, and upon the Latitude of Arbury Hill. 
By B. Be van, Esq. Communicated by Sir H. Davy, Bart. 
P. R. S. 
Read May 23, 1822. 
The Trigonometrical Survey of Great Britain having from 
time to time engaged the attention of the Royal Society, and 
circumstantial particulars of this great national undertaking 
having occupied the pages of the Philosophical Transactions, 
I beg leave to submit a few observations on that subject to the _ 
consideration of the Society. 
The result of the survey, relative to the different sections 
of the meridian, in this country, has not altogether proved so 
satisfactory as might have been expected. 
I have lately examined the calculations affected by the ob- 
servations made at Arbury Hill in the county of Northampton, 
with some hope of discovering the means of reconciling the 
anomaly in that part of the meridian. 
I have been at the expense of having the height of this 
station determined by accurate levelling to the Grand Junc- 
tion Canal, from which, and the known difference of level of 
the various canals connected with this, I have been able to 
find the relative height of this station, with most of the im- 
portant objects in the counties of Northampton, Buckingham, 
and Bedford. 
From this operation of levelling, I found the country to the 
north of Arbury station, suddenly to fall about 400 feet, and 
continue at this depressed state for 9 or 10 miles. Such a 
defect of matter, to the north of the station, was in itself a 
MDCCCXXIII. L 
