atmospherical refraction at Port Bowen. 209 
would be to observe the setting of stars within certain limits 
of azimuth, behind the high land which encircles this harbour, 
and then determining at leisure the zenith distance of that 
part behind which the star set. As the ruggedness of the 
land, however, combined with the frequent alteration of the 
star’s azimuth, would materially affect results thus obtained ; 
Captain Parry proposed, as a modification of this idea, to 
place a board edge-wise, and strictly horizontal, on the spot 
behind which the star set, thus rendering it unimportant 
upon what part of the board the occultation of the object 
took place, as well as affording more ready means of obtain- 
ing its apparent altitude. 
Two boards were accordingly fixed with all possible firm- 
ness and accuracy upon a neighbouring hill, to the westward 
of the observatory, for observing the setting of a Aquilas and 
Arcturus respectively, the board for the former being on a 
N 75 °t W bearing, distant 924 feet, and for the latter N 40° W, 
1590 feet. 
The observations by Captain Parry, given in Tables II. 
and VI., were made with a small theodolite, having its legs 
immoveably fixed by freezing, across a cask filled with sand ; 
those inTable IV.by a ship telescope,two feet in length, securely 
attached to the cask itself, and having no motion whatever. 
Lieutenant Foster’s observations contained in Tables VIII. 
to XI. inclusive, were made with a small repeating circle by 
Dollond, furnished with two telescopes, which afforded the 
means of obtaining double observations of each star the same 
evening. This instrument stood 122 feet above the level of 
the sea, on a cask filled with sand, firmly frozen to the ground, 
and was secured from the weather by a suitable covering. 
mdcccxxvi. * E e 
