.334 OF TIDES. 



The tide produced on the western coast of Europe corresponds 

 to this theory. Thus, it is high water on the western coasts of 

 Ireland, Spain, and Portugal, about the third hour after the moon 

 lias passed tiie meridian ; from thence it flows into the adjacent 

 channels, as it finds the easiest passage. One current, for example, 

 runs up by the south of England, and another by the north of 

 Scotland ; taking considerable time to move all this way, and occa- 

 sioning high water sooner in the places at which it first arrives, and 

 begins to fall at these places while the current is proceeding to others 

 further distant in its course. On its return it is unable to raise a 

 tide, because the water runs faster oft* than rt returns, till, by the 

 propogation of a new tide from the ocean, the current is stopt, 

 and begins to rise again. The tide propagated by the moon in the 

 German ocean, when she is three hours past the meridian, takes 

 twelve hours to come from thence to London bridge ; so that, 

 when it is high water there, a new tide has already attained its 

 height in the ocean, and in some intermediate place it must be low 

 water al the same time. When the tide runs over shoals, and 

 flows upon flat shores, the water is elevated to a greater height 

 than in open and deep oceans that have steep banks, because the 

 force of its motion is not broken upon level shores till the water has 

 attained a greater height. If a place communicates with two 

 oceans, or by two different openings with the same ocean, one of 

 which affords an easier and readier passage than the other, two 

 tides may a rive at this place in different times, which, interfering 

 together, may produce a great variety of phenomena. 



At several places it is high water three hours before the moon 

 comes to the meridian : but that tide which the inoou drives, as it 

 were, before her, is only the tide opposite to that produced by her 

 when nine hours past the opposite meridian. 



It would be tedious to enumerate all the particular solutions 

 easily dedticible from these doctrines: as, why lakes and seas, 

 such as the Caspian and the Mediterranean, the Euxine and the 

 Baltic, have little er no sensible tides; since, having no commu- 

 nication, or being connected by very narrow inlets with the great 

 ocean, they cannot receive or discharge water sufficient to alter 

 their surface sensibly. In general, when the time of high water at 

 any place is mentioned, it is to be understood on the days of new 

 and full moon : the times of high water in any place fall at nearly 



