Calculation, shewing in what time a permanent bridge over the river Schuylkill, supposed to cost two hundred thousand dollars, may be built and redeemed from the estimated combined product of duties on sales at auction within the city of Philadelphia and the product of bridge toll, contemplating a loan to be obtained on the credit of said combined product, so as to acquire the object of having not only a permanent but a free bridge when redeemed. ((Printed by Z. Poulson, Jun, 1798)