An essay to ascertain the value of leases and annuities for years and lives : and to estimate the chances of the duration of lives : wherein are many observations on bills of mortality, on the state of the coin, the interest of money, and the price of things in different ages : and notice taken of several writers on this subject; and their rules and tables, particularly for the valuation of annuities for one or more lives, are demonstrated to be erroneous.