"For observation purposes an astronomical telescope is not of much use
unless the movement of the earth is counteracted," he said. "Usually, the
dome of an observatory swings on a specially contrived axis, but that is
a very expensive structure, so my telescope is governed by a clockwork
attachment and moves on its own axis."

Mr. Fowler nodded. He was really a very well informed man for a country
police-officer; he understood clearly.

"Miss Martin came here about a quarter to ten," continued Grant, "and
left within three-quarters of an hour. She did not enter the house. She
was watching Sirius while I explained the methods whereby the distance of
any star from the earth is computed and its chemical analysis
determined--"

"Most instructive, I'm sure," put in the superintendent.

He smiled genially, so genially that Grant dismissed the notion that the
other might, in vulgar parlance, be pulling his leg.

"Well, that is the be-all and end-all of Miss Martin's presence. It would
be cruel, and unfair, if a girl of her age were forced into a distasteful
prominence in connection with a crime with which she is no more related
than with Sirius itself."

The older man shook his head in regretful dissent.

"That is just where you and I differ," he said. "That very point leads us
back to your past friendship with the dead woman."