ite wing. First one wing is rubbed over the other,
and then the process is reversed.

A near relative of the grasshopper, the cicada of North America and of
Southern Europe (fig. 2), has a really wonderful instrument, rather like
a kettle-drum. But it is an unusual sort of kettle-drum, for it is
played from within. The drum-heads are shown in fig. 3, marked D, one on
each side of the creature, like the drums on a cavalry horse, except
that they are underneath the animal in the case of the cicada. If the
'skin' of the drum be removed, a very complicated instrument is seen,
and this, by causing vibrations, increased by the tightly stretched
drum-head, gives rise to the sounds for which these insects have long
been famous.

The great traveller-naturalist, Fritz Mueller, tells us that musical
contests between two or three rival cicadas--only the males play--often
take place. As soon as one had finished his song, another immediately
began, then another, and so on all through the night. Another
naturalist, Bates, tells that when in the Amazons he used to listen to
the cicadas, which began with sunset. The tune began with a jarring
sound, and ended in a long loud note, like 'the steam-whistle of a
locomotive engine!'

In insects which hum the sound mainly comes from the abdomen. In flies
and humble-bees, for example, the 'voice' is caused by air rushing out
from the mouths of the air or breathing-tubes. But these sounds are
deepened by the vibration of the wings. Those who know something of
music will understand what is meant when they are told that the note of
the honey-bee on the wing is A; its ordinary 'voice,' however, is an
octave higher, and often goes to B and C. From the note produced by the
wing, the speed with which it is vibrated can be reckoned. Thus, the
house-fly, which produces the sound F, vibrates its wings 21,120 times a
minute, or 335 times a second; the bee, which makes the note A, 26,400
times a minute, or 440 times a second!

But, besides insects, there are many spiders and scorpions which may
claim to be musical. The instrument of the spider is formed on the same
principle as that of the grasshopper--that is to say, by a raised
tooth-like edge, which can produce vibrations. Beneath the front of a
spider's head there is, on each side, a stout jaw, ending in a long,
movable fang, like a claw. Behind this jaw is a short leg, formed like a
walking leg, and known as the 'palp.' It is never used, however,