AN ANSWER TO THE OBJECTIONS OF THE Citizens of YORK, AGAINST The Bill for making Navigable the River's Air and Calder.  
IT is objected, That if these Rivers (or either of them) be made Navigable, it will so drain and lessen the Tide of Ouze, as to render that River Vnnavigable for the future, to the great Damage of the City of York.  
In answer thereto, It is humbly conceived, that it can have no such Effect for the following Reasons: 

1st, The Objection does not reach the River Calder, for that River empties itself into Air, many Miles above the Flowing of the Tide; so that whatsoever is done upon that River cannot affects the Tides, and therefore is out of the Question.  
2ly, Nor has the Objection any greater force against making the River Aire Navigable; For tho' the Cause of the Ebbing and Flowing of the Sea is not yet discovered, yet it must be granted, That the Ebbing and Flowing of the Sea is the only Cause of the Tide in all Rivers where it is; And that the Effect necessarily attends this Cause is Matter of Fact and Daily Observation, the Tides being always greater or less, as the Waters rise more or less at Sea; And the greatest Rivers are filled as high (viz.) as near to a Level with the Swelling of the Sea, as the least are, every Tide, tho' they contain a hundred times as much Water; and consequently, tho' the whole County of York were dug into a Pond, or Receptacle for Water, it could not lessen the Tide in any other proportion than the Water contained in that Receptacle would bear to the neighbouring Seas, from whence it was supplied; and that quantity of Water would be but a small part of the whole, and could not abate the Surface of the Tide-Water a quarter of an Inch: For Water acts mechanically and necessarily, as a heavy fluid Body, and will flow naturally to all Places where the Surface is lower than the Place it flows from, and fill them all (tho' never so large) till all the Surface is at equal distance from the Centre, and then it becomes its own poise and is at rest: From whence it plainly follows, That nothing can be done upon the River Aire, to lessen sensibly the Tide of Ouze. 
There might be given many Instances to confirm this Argument, (were it needful) As when the Banks break in Holland and Zealand, (which often happens) whereby the Receptacle for the Tide-Water is much more enlarged than can be pretended in the present Case, and yet the Tide in the next Rivers not lessened (to sense). Likewise, since the breaking of the Banks upon the River Thames (in Essex) whereby the Outlet for the Water has been greater than is feared in this Case, the Tides have not been less at London-bridge.   
3ly, But admitting there were any force in this Objection, it makes for the Navigation of Air, and not against it; For, if the making the Receptacle for Water in the River Aire greater, will lessen the Tide in the River Ouze (as objected)— Then the making the Receptacle in the River Aire less, will increase the Tide in the River Ouze.    
And that is what the Undertakers for Air will do, (if they altar the River at all) for they will make the Course or Channel of the River straiter, and then the Water taking this new Course, the old crooked Channel will soon fill up, and consequently the River Aire contain less Water than before, being made much shorter and narrower than it was. But if they do not alter or meddle with the River Air within the flowing of the Tide, (as is most likely) Then this Objection reacheth the Navigation of Air no more than Calder, but answers itself.