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Art. II.— -Oti the Tides qf the Mediterranean^ and the occa^ 
sional luminous appearances of its Waters. By Henry Ro- 
bertson, M. D. Member of the Literary Society of Athens, 
Physician Extraordinary to his Royal Highness the Duke of 
Kent, &c. Communicated by the Author. 
HILE at Venice, in the montlis of April and May ISIT, 
I was very much surprised by perceiving the regular succession 
of tides in the Mediterranean, surrounding that city, as I was 
by no means prepared to expect this, either by previously con- 
versing with travellers on subjects of inquiry regarding that sea, 
or by what had occurred to myself during a residence of several 
years on other parts of its coasts. It is a commonly received 
opinion, that there are no tides in the Mediterranean, an opi- 
nion which, with the exception above mentioned, I am not dis- 
posed to dispute ; at the same time, from attentive observation, 
I am persuaded that the Mediterranean Sea does undergo a sensi- 
ble elevation and depression of its waters ; which regularly re- 
cur within the twenty-four hours, but which are by no means so 
remarkable, or perhaps so regular, as the ebb and flow even of 
the neap-tides in the ocean. 
On the open shores of the Mediterranean, the highest eleva- 
tion, and greatest depression appeared to me to be about two 
feet in calm weather ; it also appeared greater at periods cor- 
responding to the spring-tides of the ocean, and was greatly in- 
creased on the blowing of the wind towards the coast. I have 
also observed a regular recurrence of the tides in that part of 
the Mediterranean surrounding Venice. Within its entrance at 
Malomocco, the tides are regular, an ebb and flow taking place 
every twelve hours, in which it appeared to me that the waters could 
not be less elevated than from eight to ten feet. This I estimated 
by seeing, that on the flow, boats easily floated over banks that 
at the ebb were dry, and elevated several feet above the water, 
and which I had an opportunity of remarking for the period of 
eighteen days, from the windows of the Lazaretto. 
* The Chevalier D’Angos obrerved a rise of me foot at Toulon three and a 
half hours after the Moon passed the meridian. — Ed, 
