OS CUM
MAGUS AB URBE PUELLOS
DUXERAT ANTE ANNOS
CCLXXII CONDITA
PORTA FUIT._'[1]

"The same story is found, with variations, in all parts of the world.
There is, for example, the story of the wicked Hatto, abbot of Fulda. He
was visited by a swarm of rats who killed him. I can give you a dozen
variations of that story, but in each of them the rats came and went,
suddenly, as Mr. Willowby says they have been doing in New York."

"I should like to see a few examples of this mass movement of rats. I
saw a lemming migration in Norway, but that was different," explained
Rastell. "It seems to me that if we actually saw one of these nocturnal
attacks, we might learn why they wanted to do it."

"He is deadly right," agreed Professor Wilson. "A few actual facts are
worth a hundred theories."

"That is why I have asked you to help me," explained the richest man in
New York. "I have prepared some experimental stations for your use. I
can put you in a grocery warehouse and guarantee that inside of a week
you will see more rats than you ever dreamed of. I have a laundry and a
small hotel. We can work out the details right now. All I am asking of
you is to find out, when the rats come, _why they come_ and, once we
know that, we can do something to solve this problem."

"The game looks interesting," declared the Professor of rat psychology.
"What I am interested in is why the rats do it. I am sure that it is
because they want to do it, but are they forced to want to do it? It is
a problem that will take a lot of research to solve, but Rastell and I
can solve it. With all respects to our friend, Mr. Crawford, I think
that he had better stay away and just keep on reading about his little
pets. A few thousand vicious rats would be hard for him to deal with."

"I guess you are right," laughed Winifred Willowby. "Crawford and I will
stay here and read about it while you two do the actual scientific work.
By the way, Crawford, in that story of the Piper, what was given the
credit for drawing the rats out of the town?"

"The tune that he played on the pipes!"

"Check and double check. Now I would advise you gentlemen to locate some
musical instrument in that warehouse, and if you find one, experiment
with it. Of course, you will have to be rather clever to find it. In the
first place, the people putting it there will have it under cover and
just as soon as the mischief is done they will remove it."