- bo ats . ▁It ▁included ▁the ▁Australian ▁phys ic ist ▁William ▁Henry ▁B rag g ▁and ▁the ▁New ▁Zealand ▁phys ic ist ▁Sir ▁Ernest ▁R uther ford . ▁ ▁They ▁concluded ▁that ▁the ▁best ▁hope ▁was ▁to ▁use ▁hydro ph ones ▁to ▁listen ▁for ▁sub mar ines . ▁R uther ford ' s ▁research ▁produced ▁his ▁sole ▁pat ent ▁for ▁a ▁hydro phone . ▁B rag g ▁took ▁the ▁lead ▁in ▁July ▁ 1 9 1 6 ▁and ▁he ▁moved ▁to ▁the ▁Admir alty ▁hydro phone ▁research ▁establishment ▁at ▁Haw kc ra ig ▁on ▁the ▁F irth ▁of ▁For th . ▁▁ ▁The ▁scient ists ▁set ▁two ▁goals : ▁to ▁develop ▁a ▁hydro phone ▁that ▁could ▁hear ▁a ▁sub marine ▁despite ▁the ▁ra cket ▁produced ▁by ▁a ▁pat rol ▁ship ▁carrying ▁the ▁hydro phone ▁and ▁to ▁develop ▁a ▁hydro phone ▁that ▁could ▁reve al ▁the ▁bearing ▁of ▁the ▁sub marine . ▁ ▁A ▁bid irection al ▁hydro phone ▁was ▁invent ed ▁at ▁East ▁London ▁College . ▁ ▁They ▁mounted ▁a ▁micro phone ▁on ▁each ▁side ▁of ▁a ▁dia ph rag m ▁in ▁a ▁cyl ind rical ▁case ; ▁when ▁the ▁sounds ▁heard ▁from ▁both ▁micro ph ones ▁have ▁the ▁same ▁intensity , ▁the ▁micro phone ▁is ▁in ▁line ▁with ▁the ▁sound ▁source . ▁▁ ▁B rag g ' s ▁labor atory ▁made ▁such ▁a ▁hydro phone ▁direction al ▁by ▁mount ing ▁a ▁b aff le ▁in ▁front ▁of ▁one ▁side ▁of ▁the ▁dia ph rag m . ▁ ▁It ▁took ▁months ▁to