Kendrick, while confined in a federal institution at Lompoc, California, wrote two threatening letters to the trial judge who entered the judgment that sent him *633 there. The letters reached the judge through the mail.

Kendrick mainly attacks the sufficiency of the evidence. His defense was that he never thought that the letters would get through the censors and into the mails. But he put the letters on a ledge outside his cell, a place where mail was ordinarily picked up by prison personnel. He had no direct access to an official United States mail box.

Kendrick’s testimony did create an issue of fact as to his intent. This, the jury decided against him. The circumstantial evidence was such that the jury could find him guilty beyond a reasonable doubt, if it chose to disbelieve him. And, it did so.

We find no error in the instructions.

Judgment affirmed.