ABSTRACT
W h il e it m ay be reasonable to assum e th a t some of the results which have been described in previous chapters will eventually be capable of practical application, it m ust be adm itted th a t such applications are, as yet, in their infancy. Still, as “ infant welfare ” is now recognized as w orthy of intensive study, an account of th e first a ttem p ts in th e use of m ultiple resonators m ay be of interest.
