to my eye. The light of this bulb is reflected in a mirror which
is moved by the moving needle. When the sound is loudest the two
horns are at right angles to the direction whence it comes. So it
is only necessary to twist the phonometer about on its pivot until
the sound is received most loudly in the horns and the band of
light is greatest. I know then that the horns are at right angles
to the direction from which the sound proceeds, and that, as I
lift my head, I am looking straight toward the source of the
sound. I can tell its direction to a few degrees."

I looked through it myself to see how sound was visualized by
light.

"Hush!" cautioned Kennedy.

Down on the main road we could see a car pass along slowly in the
direction of Montrose, from which we had come. Without the
phonometer to warn us, it must inevitably have met us and blocked
our escape over the road ahead.

That danger passed, on we sped. Five minutes, I calculated, and we
should cross the State line to New York and safety.

We had been going along nicely when, "Bang!" came a loud report
back of us.

"Confound it!" muttered Kennedy; "a blowout always when you least
expect it."

We climbed out of the car and had the shoe off in short order.