THE EXPANDING UNIVERSE (Presentation copy signed by Edwin Hubble)

First edition: vii, 128 pages, frontispiece, 1 plate illustrating the spectra of nebulae, half title page, green cloth boards slightly faded, with gilt title on the spine which has faded to brown, a good copy.

Presentation inscription on the half title page reads: For Capt. Reginald Berkeley. My dear Reggie, This book is a souvenir of a night on Mt Wilson where we two explored some of the more remote regions of space with the 100 - inch and looked back many millions of years into the dim past. Edwin Hubble. Feb.1934 Mt.Wilson Observatory.

Sir Arthur Eddington was one of the most prominent and important astrophysicists of his time. He was one of the first physicists to understand the early ideas of relativity along with Albert Einstein. ESA's planet-finding mission Eddington is named after him.
For a detailed biographical sketch see: 
https://www.esa.int/Science_Exploration/Space_Science/Studying_the_stars_testing_relativity_Sir_Arthur_Eddington

 Edwin Powell Hubble (1889-1953) for whom the Hubble Space Telescope is named, was one of the leading astronomers of the twentieth century. There is Hubble's zone of avoidance, the Hubble galaxy type, the Hubble sequence, the Hubble luminosity law for reflection nebulae, the Hubble luminosity profile for E galaxies, the Hubble constant, the Hubble time, the Hubble diagram, the Hubble redshift-distance relation, the Hubble radius for the universe, and now the Hubble Space Telescope. This historic inscription by Hubble celebrates the memory of a scientist whom some have called the greatest astronomer (in changing paradigms) since the times of Galileo, Kepler and Newton.
For further details on the life of Hubble, written by the late Allan Sandage see:
https://apod.nasa.gov/diamond_jubilee/1996/sandage_hubble.html