Harry Schmidt 
Relativity and the Universe [PDF ebook] 
A Popular Introduction Into Einstein’s Theory of Space Time

Whilst the greatest effort has been made to ensure the quality of this text, due to the historical nature of this content, in some rare cases there may be minor issues with legibility. I have to express my thanks to Dr. Karl Wichmann for kindly offering me an opportunity of inserting the corrections mentioned. It would cause me much pleasure if this English edition should contribute to the great object of spreading, as widely as possible, a knowledge of the fundamental ideas of Einstein’s theory of relativity.