They are of much use to firemen when giving orders at a fire, and to those on board of vessels when giving orders to the sailors.
Why do we hold the hand behind the ear when we wish to hear more distinctly?
Because the hand catches more of the waves of sound, and conducts them to the ear.
What instrument has been made to serve the same purpose?
The ear-trumpet, as is shown in [Fig. 25].
Fig. 25.
How does the ear-trumpet aid the hearing?
The large end of the trumpet collects more of the waves of sound than the ear can; hence, more waves reach the ear.
Why do such animals as the horse, the rabbit, and the deer, hear better than we do?