122 
Gen . Roy’s Account of 
But befides the danger of having the glafs rods broken, in 
trap {porting to fo great a diftance from London, and, on fuch 
an event happening, the impoffibility of getting them replaced 
with others at the advanced feafon of the year in which we 
were unfortunately thrown with the operation, it was obvious, 
that in a plain of the breadth of fix miles, fo much inter- 
fered with ditches full of water as Romney Marfti in reality 
is, the laying of bridges for the tripod {lands, which mu ft have 
been ufed with the glafs rods, would alone have been a very 
troublefome and tedious operation. 
Art. II. Beech Pojis . 
In the firft place, about thirty pofts made of beech wood, 
three inches in diameter, and of different lengths, from two 
feet three inches to three feet fix, and a few of them ftill longer, 
were provided. They were fhod with iron, and each of them 
carried on its top a caft-iron ferrule, with two dovetails project- 
ing from it ; care being taken in driving them into the ground, 
that the dovetails fhould ftand in or nearly in the direction 
of the bafe, as reprefented by the plan and fe&ion of a lingie 
poft, in the middle part of Plate I. The arrangement of 
twenty- four of thefe pofts may be feen at the top of the faid 
plate, for the meafurement of a portion of the bafe equal to 
one hundred yards, or the length of three chains. Sixteen of 
the pofts reckoning from that which ftands in the center of 
the firft group, to that which ftands in the center of the fe« 
cond, and fo on from right to left, were placed at the diftance 
of twenty feet from each other. The firft is fuppofed to co»in- 
cide with the mouth of the pipe funk into the earth, at the 
eaftern extremity of the bafe, at a place called High Nook 
near Dymchurch ; and every fifth poft from that towards the 
left 
