Hydraulic ORGAN, denotes a musical machine that plays by water instead of wind. Of these there are several in Italy, in the grottos of vineyards. Ctesibes of Alexandria, who lived in the time of Ptolemy Euergetes, is said to have invented organs that played by compressing the air with water, as is still practiced. Archimedes and Vitruvius have left us descriptions of the hydraulic organ.
In the cabinet of Queen Christina is a beautiful and large medallion of Valentinian, on the reverse whereof is seen one of these hydraulic organs; with two men, one on the right, the other on the left, seeming to pump the water which plays it, and to listen to its sound. It has only eight pipes, placed on a round pedestal. The inscription is PLACER SPETRI, if it be not wrong copied, which we suspect to be the case.
ORGASM ὀργασμός, denoting violence or turgescence; formed from ὄργας, turgio, "I swell," an ecstasy or impetuous desire of coition, occasioned by a turgescence of the seminal vessels, which are no longer able to restrain their contents. The ancients also ex-
tend orgasm to the other humours, and even excrements, which being accumulated, and coming to fermentation, demand excretion. Quince uses orgasm for an impetuous or too quick motion of the blood or spirits; whereby the muscles are distended with an uncommon force.