Algebraic expressions for the amplitude and phase of the zero power transfer funciton allow these quantities to be evaluated from measured precursor data without the use of a digital computer. The asymptotic forms of the amplitude and phase for large and small values of ω are particularly simple. The expressions show the conditions under which the gain should be frequency-independent and yield a simple formula for the angular frequency ω0 at which the phase angle reaches a maximum. The inhour relation is shown to be intimately related to the transfer function, the reactivity in dollars for any period α−1 less than one second being equal to 1 − tan ε, where ε is the phase angle at ω = α. The value of α corresponding to prompt critical is shown to be always equal to ω0.