 How did Ninian, Raymond, and the other cousins go back in time?
Besides, if she really was his great-great-grand-daughter, as she said, why would she tell him to call her " Aunt Ninian "? From time to time, there were other visitors—Uncles Ives and Bartholomew and Olaf, Aunts Ottillie and Grania and Lalage, and many more—all cousins to one another, he was told, all descendants of his. It was then that Martin began to realize that either the whole lot of them were insane, or what Ninian had told him at first was the truth. When Martin was sixteen, Raymond took him aside for the talk Ninian had promised five years before. And, on those worlds, it's far cheaper to use native labor than to ship out all that expensive machinery.
 They bribed the assistant for the plans and blackmailed or tortured someone to build the time transmitter for them.
 They bribed the assistant for the plans and blackmailed or tortured someone to build the time transmitter for them.  Professor Farkas' assistant sent them back in time using the time transmitter after they gave him a bribe.  They bribed the assistant for the plans and hired a gadget enthusiast to build the time transmitter for them.  Professor Farkas sent them back in time with the time transmitter.