44? 2 The Account of a 
period, to compare the results from the data afforded by the 
trigonometrical operation, with those deduced from the astro- 
nomical observations made by the above gentleman. It may 
be also mentioned, that angles were at the same time taken at 
the western light-house and signal-staff, for the purpose of 
finding the situation of the Lizard Point. 
We are now to speak of the most important business per- 
formed this year; that of making observations to determine 
the distance of the Scilly Isles from the Land’s End. 
To do this as accurately as possible, it became necessary to 
find stations affording the longest base. The hill near Rose- 
mergy , called the JVatcb, and the station near St. Buryan, are 
certainly the most advantageous places, because all the islands 
can be seen from both ; but we could not avail ourselves of the 
former, as difficulties almost insuperable would have attended 
an attempt to get the instrument upon it. Another station was 
therefore selected, on Karnminnis, near St. Ives; a spot as well 
situated as the place spoken of, provided all the islands could be 
seen : this, however, does not prove to be the case, St. Martins 
Day-Mark being the only object in the Scilly Islands visible 
from Karnminnis. 
From the stations near the Land's End (Sennen and Pertin- 
ney), as well as that above mentioned (St. Buryan), St. Agnes’ 
Light-house, and two objects in St. Mary’s, were observed; 
and as the means by which all their distances are determined, 
except those of the Day- Mark, from the shortness of the bases 
(which were, however, the longest that could be found) are 
exceptionable, it will be right to mention, that while we were 
engaged in that part of the operation now spoken of, the air 
was so unusually clear, that we could sometimes, with the 
