G2 
MR. LLOYD’S ACCOUNT OF LEVELLINGS 
assisted by a Spaniard whom I had previously instructed in the management 
of the station staff. By means of signals I made him adjust the cross-piece 
correctly to the horizontal wire of the telescope ; he then brought me the 
staff, which I read off and noted down the reading ; he resumed his station, 
1 examined the level again, adjusted the staff, recalled the Spaniard, and 
read off a second time. 
From the Chagres to the last level my companion had the station staff 
himself, which when adjusted to the cross-wires was read off by him. I then 
re-examined the level, adjusted the staff a second time, and he again read off, 
writing down the two observations in distinct books, which were compared in 
the evening. The instrument itself I proved on most days after work, by 
making a set of 8 or 10 levellings in a circle ; returning in the last station 
to the point from which I first started, and finding the sum of the differences 
of the levellings amount to zero. 
The point from which the levellings commenced at Panama is marked by 
a large stone cut for that purpose in the wall at the edge of the sea in Playa 
Prieta ; and the concluding point at La Bruja, by a tree cut down to the exact 
height marked in the Observation Book above the surface of the water : the 
height of the section of the tree is G.848 feet below the level of high-water 
spring tide at Panama. No better means of marking this level presented itself 
at La Bruja ; but by a reference to the manuscript detail of the observations 
preserved in the library, several stations are to be found in the vicinity which 
are not liable to decay. 
By careful and continued observations, I found the rise and fall of the tide 
in the Pacific at Panama as follows : between the extreme elevation and 
depression of the waters by occasional tides there is a difference of 2/.44 feet, 
and the mean actual rise and fall two days after full moon is 21.22 feet. 
At Chagres I observed the rise and fall of the tide at the close of the dry 
season in April 1829 to be 1.1G foot, and being there subsequently during the 
rainy season, I had an opportunity of observing that the high-water mark was 
the same in both seasons. 
The time of high water is nearly the same at Chagres and at Panamfi, namely 
at 3 h 20 m at full and change: hence the following interesting and curious phe- 
nomena arc deductible in respect to the difference of level of the two seas. 
First. — Iligh-water mark at Panama is 13.55 feet above the high-water mark 
