Trigonometrical Survey. 441 
use of on account of the ruggedness of its surface, which seems 
to render the carrying of the instrument to its top almost im- 
possible. From this circumstance, and similar impediments, 
which the high lands remote from the circumference of Dart- 
moor offer to our operations, it results, that the body of this' 
moor cannot have any great triangles carried over it : such 
stations were therefore selected this year as may serve, in 
conjunction with others, to include this tract of country in a 
polygon of a small number of sides. 
To make observations for the purpose of hereafter deter- 
mining the longitude and latitude of the Lizard, was a prin- 
cipal object in this yearns operations ; and as this headland 
seems to offer itself as very convenient for a station, it will be 
right to assign our reasons for not having chosen one upon it. 
As no other spot but Hensbarrow Beacon could be found in 
that part of Cornwall proper for a station, it became necessary 
to fix on the Deadman, or Dodman, for another point in the 
series. From this place no part of the land within four miles 
of the Lizard can be seen, as the high ground about Black 
Head, which is to the eastward of the latter, is nearly in a line 
between them, and is also much higher than both. It will be 
perceived, however, that no evil can result from the want of 
such a station, as the light-houses and the naval-signal-staffi 
at the Lizard, have been intersected from several stations. The 
precise spot on which Mr. Bradley made his observations in the 
year 1769, for ascertaining the longitude and latitude of this 
headland, was pointed out by the person having the care of 
the light-houses, who well remembered the common particu- 
lars relating to his operations : such measurements were made 
from the light-houses to this spot, as may enable us, at a future 
