Notes
The Time Hoppers, a standalone novel by Robert Silverberg.

Previously published in a shorter form as Hoppers in Infinity Science Fiction (October 1956).

The image opposite and the blurb below are from the 1968 Sidgwick & Jackson hardback edition, SBN 283354917. Cover designer unknown.

Publisher's Blurb – Upper and Jacket Flap
It is Joseph Quellen's job (as a member of the Secretariat of Crime) to stop the one-way traffic of time-travel to the tranquil past – humanity's escape from the crush and bore-dom of the twenty-fifth century. Quellen's dilemma, as for others, is that the timing is all wrong. Is there really a way out?

The author of this new story, Robert Silverberg, is a well-known and prolific SF writer, and a winner of the coveted Hugo Award.

Robert Silverberg's lively imagination and capacity for bringing it to life in words is evident in this tale of time-travellers from the year 2490.