Comet-4, by N C Baldwin.

Published by House of Antiquity.  S/B, 16pp.

This reprint of a title in Francis J Field's 'Popular Pamphlet' series lists first mail flights with the Comet-4 aircraft.  Listings are arranged alphabetically by the country in which the flights originated.  Examples of aerogrammes, cachets, and covers are illustrated in black and white.