matter how many of their
scientific secrets they gave us. Dad and I exhibited ourselves, but I
don't know yet what the Martians look like--though I have made a
guess.

"By the end of the third year they had showed Dad how to make one of
those metal things--"

"Like that one that jumped at me?" Dan broke in with a shudder.

"Yes. They seem almost alive; but they are machines, like our robots,
and controlled by the radio apparatus. The eyes use photo-electric
cells, and relay what is before them to the Master Intelligence." The
girl spoke these last words in a low tone, shrinking involuntarily.
She paused a moment, then shrugged and continued.

"The first machine did not obey my father. It was controlled by
signals that came from Mars, over the big station on the hill. And it
went to work, making more apparatus, building more machines, enlarging
the receiving station. It worked in obedience to the Master
Intelligence on Mars!

"That was a year ago. The last time the yacht called, my father and
the other men still hoped to control the machines. They let her go
back without us. The machines tolerated us a while; paid no attention
to us; they were busy working mines and building huge, strange things
that must be flying machines; the plateau on the other side of the
peak is crowded with them.

"For the machines are preparing to leave the island! They are going to
conquer the world for the Master Intelligence on Mars!

"Months ago my father discovered this, and realized that he had loosed
doom upon the earth. He and the three other men planned to destroy
that big station on the peak. All the signals to the machines are
relayed through that, from Mars. The machines seemed to pay no heed as
they made their preparations.

"Then one night, about three weeks ago, they tried to dynamite the
station." The girl's shoulder trembled; she paused to brush a tear
from her eye, then went on hastily, in a voice grown husky with
emotion. Dan felt an odd desire to take her slight form in his arms
and comfort her in her grief.

"The machines had seemed heedless, but they were ready. They had those
disks that throw the green fire: we had not seen them before.
And--well, all four of them were killed."

Dan handed her the disk of green crystal he had taken from the thing
that had attacked him. She examined it silently, then went on.

"Dad had left me in bed, but I heard an explosion. I think the bombs
went off when the green fire s