* * * * *

Two or three days after something new happened; an old thing happened
freshly, rather,--which also had to do with our orbit and its
eccentricities. Barbara, as usual, discovered and announced it.

"I should think _any_ kind of an astronomer might be mad!" she
exclaimed. "Periods and distances are bad enough; but then come the
perturbations! Here's one. We're used to it, to be sure; but we never
know exactly where it may come in. The girl we live with has formed
other views for herself, and is going off at a tangent. What _is_ the
reason we can't keep a satellite,--planet, I mean?"

"Barbara!" said mother, anxiously, "don't be absurd!"

"Well, what shall I be? We're all out of a place again." And she sat
down resignedly on a very low cricket, in the middle of the room.

"I'll tell you what we'll do, mother," said Ruth, coming round. "I've
thought of it this good while. We'll co-operate!"

"She's glad of it! She's been waiting for a chance! I believe she put
the luminary up to it! Ruth, you're a brick--moon!"




CHAPTER VI.

CO-OPERATING.