1 -The reasons I otter to account for ,t‘*~ c 1!n - 
stance of these lights appearing q ute clou a to 
the horizon, notwithstanding they exist very 
high, arc as follows:—When I stand on toe lace 
of a hill, and look over a valley at the face of an 
Opposite hi 1, the opposite hill appears to ue more 
steep than.real:«—when navigating' a small \vatei 
i craft through shallow water, the vwuei ahead 
continually appears mere shallow than real. 1 
ascribe both these circumstances to the princi¬ 
ple of refraction; and hence conclude by apply¬ 
ing the principle tq the clouds,—that the far¬ 
ther part of the lower side of a cloud is apparent¬ 
ly bent downwards, just as the farthest part of 
the face of the opposite hill is bent upwards ; so 
that tlie clouds which are really 45 deg. high, 
appear lower than re;d, and seem to hang down¬ 
wards, however broadly horizontal their real 
form mu', be; if this principle does not appear to 
elevate the surface of the earth towards the 
clouds more than real, it at least depresses the 
clouds apparently towards the eartl^inore than 
real. It a person,were standing by a column 
half a mile high, and a stratum of clouds was 
even with the top of the column, and another 
similar column stood 30 or 30 miles distant, also 
reaching to the-same stratum of clouds, such 
distant column would appear .Very short; some¬ 
what owing to the curviture of the earth, but 
principally owing to the apparent contraction of 
the column ; which contraction is chargeable to 
its distance frointbe observer: If such column,thus 
distantly situated, would appear to an observer 
at the first mentioned column, apparently but a 
few icet high, the clouds at its head, must appear 
| to come quite to tlie ground a little space be¬ 
yond the foot of the column; admit this, and 
it follows, that an serial sphere when visible, 
must, like a stratum of clouds, soon apparently 
sink to the earth. * . 
I am not at present able tn offer any satisfacto¬ 
ry reason why we should not see these lights 
southwards of us as well as northwards may it 
be owing to the spheres nearing each other on 
the side reverse from the equator, especially in 
the winter of each hemisphere respectively ? 
I believe experienced observers have general¬ 
ly estimated the plane in which the northern 
hglns occur, as about sixty miles above the sur¬ 
face of the earth ; perhaps they sometimes exist 
in several different and succeeding spheres at 
the same time, one above another. 
JNO. CLEVES SYMMES. 
