ou came sliding across to our window on
that plank. _That_ was so ridiculous!"

"Just so," responded Harris, calmly. "Now, please be still, young ladies
and--watch the professor!"

And for an hour the girls did actually manage to keep as still as mice.
Their friend certainly was absorbed in the work before him. He tested
one sample of water after another, and finally went back and did the work
all over upon one particular bottle that he had brought down from Spink's
hiding place among the rocks.

"Just as I thought," he declared, with a satisfied smile. "And just as
father suspected. Prepared to be surprised--pleasantly. Your Aunt Jane
must be warned not to sell Hillcrest at _any_ price--just yet."

"Oh, why not?" cried 'Phemie.

"Because I believe there is a valuable mineral spring on it. This is a
sample of it here. Mineral waters with such medicinal properties as this
contains can be put on the market at an enormous profit for the owner of
the spring.

"I won't go into the scientific jargon of it now," he concluded. "But the
spring is here--up there among the rocks. Spink knows where it is. That
is his secret. _We_ must learn where the water flows from, and likewise,
see to it that your Aunt Jane makes no sale of the place until the matter
is well thrashed out and the value of the water privilege discovered."

CHAPTER XXIX

AN AUTOMOBILE RACE

Lyddy was to write to Aunt Jane the next day. That was the decision when
Harris started for town after breakfast, too. No time was to be lost in
acquainting Aunt Jane with the fact that the old doctor spoke truly when
he had said that "there were curative waters on Hillcrest."

In Dr. Polly Phelps's day a mineral spring would have been of small
value compared to what it would be worth now. Jud Spink, of course, had
known something about the old doctor's using in his practise the water
from somewhere among the rocks. On the lookout for every chance to make
money in these days, the owner of "Stonehedge Bitters" and "Diamond
Grits--the Breakfast of the Million" had determined to get hold of
Hillcrest and put the mineral water on the market--if so be the spring
was to be discovered.

Too penurious to take any risk, however, Spink had wished to be sure that
the mineral spring was there, and of its value, before he risked his good
money in the purchase of the property.

The question now was: Had he satisfied himself as to these facts? Had he
found the mineral s