Mr . Huddart’s Observations 
38 
cut the land higher, as at H O, H O, yet the point had always 
the same appearance as a, a , a , fig. 6 , though the land is known 
to continue in the direction of the straight line A B to beneath 
the horizon, or nearly so, as viewed from the height above. 
If then from a low situation we view this head land througli 
a telescope, the inclination of the surface A B to the horizon 
being known to be a straight line, it will appear as in fig. 7 . 
the dotted line (at the height of the point where a perpendi- 
cular x y would touch the extreme of the land) being at the 
limit or lowest point of erect vision. And if a tangent to the 
curved appearance of the land a b, is drawn parallel to the in- 
clined surface of the land A B, fig. 6, touching it at C, the 
point C will shew the height of the maximum of density, 
where the pencil of the rays of light, from thence to the eye, 
approach nearest the sea ; for pencils of rays from this land, 
taken at small distances from C, will form parallel curves, 
nearly, through the refracting mediums, and C will be the point 
of greatest refraction; for above C as at B the refraction 
somewhat decreasing, will appear below the line a b, or the pa- 
rallel to the surface of the land, and the refractions decrease 
below the point C ; for had they increased uniformly down to 
the surface of the sea, it would render the apparent angle of 
the point of land % more acute than the angle C a O, contrary 
to all observations. 
Thus I have endeavoured to explain the phenomena of the 
distorted appearance of the land near the horizon of the sea, 
when the evaporation is great; and when at the least, I never 
found the land quite free from it when I used a telescope ; and 
from thence infer, that we cannot have any expectation to find 
a true correction for the effect of terrestrial refraction, by tak- 
