This book reminds me of the TV series - Dr. no. Only not nearly as good. All time travel stories share a common need for a stretch in plausability. This one seems to have almost none. You can't take your machine with you and must have a machine wherever you travel to in order to get back. Or, maybe not if you can align yourself along a meridian at the precise time of a disturbance in space/time. Nah! This falls way down my list of time travel reads. At the end I had to ask myself "was it really worth the journey?"