Color of the Aur and of Deep Waters. 71 
it known. Their account excited public curiosity, and boats of con- 
venient size were made which now serve to introduce amateurs. Its 
entrance is triangular, having a base of four feet five inches wide and — 
about the same height. _‘The summit is rounded and having but lit- 
tle thickness, the entrance is easily effected by stooping, when the 
traveller finds himself in a spacious grotto, the sides and roof of which 
are remarkably regular. Its extent from the front to the rear, which 
is the only landing place, is one hundred and twenty five feet and it 
measures one hundred and forty five feet in a transverse direction. 
The depth of water at the entrance is sixty seven feet, in the middle 
of the grotto sixty two feet and at the landing place fifty eight feet. 
The rock is limestone of a clear grey fracture, and there are no indi- 
cations of stratification. 
On entering, every thing appears dark except the water which is 
luminous and of a splendid blue, contrasting with the general obscu- 
rity. In advancing from the entrance the ends of the white oars 
shine in the water with a splendid blue light which disappears as soon 
as they are raised: this is the most singular phenomenon of the azure 
grotto, for people are puzzled to conceive why objects are so vividly 
luminous in the water, and no longer so when above the surface. In 
dipping the hand or a cloth into the water one would think it a blue 
dye; the whole immersed part is luminous and colored, while the 
parts without are dark and uncolored. 
At the bottom of the grotto there is a small space on a level with 
the water, where debarkation is effected, and which is the only spot 
which leads to any suspicion of the work of human hands in the grot- 
to. It is a kind of bench in the rock about three feet high, on which 
several persons may conveniently place themselves and examine at 
leisure the phenomenon of the azure grotto. The light which comes 
in at the small opening, produces a train of white light, like the re- 
flexion of the moon from the water when rising, and which extends 
half way over the sheet. ‘The rest of the surface is blue even to the 
feet of the observer. This color gradually diminishes to the right 
where the walls of the grotto are farther from the entrance. The 
train of white light, illuminates also the vault and exhibits it in its 
natural color, but when the entrance is closed by a boat or more per- 
fectly by a dark cloth the vault itself becomes blue, reminding one of 
the effect of burning spirits of wine in a dark chamber. There is 
then no light but that which proceeds from the water. ‘The experi- 
ment of the cloth ought to be made by all who wish to enjoy the spec- 
tacle in its full beauty. 
