Robin Crosbie will begin her new post as town manager on Aug. 1. She was hired by the Board of Selectmen last month. Crosbie arrives from Longmeadow, where she served as town manager for six years. She previously worked as a town administrator in Hadley. In the last year, two people have held the post and taken other positions. Bob Markel left in January, and Thomas Younger, who served as interim town manager, is now the town administrator in Swampscott.