Joseph Baldwin was the third and last of the Victorian Government Astronomers. His grandfather had been an eminent astronomer in Britain, and Baldwin took an early interest in astronomy, working at Melbourne Observatory between finishing high school and commencing his studies in physics and mathematics at the University of Melbourne.
After completing his degrees, he was awarded an 1851 Exhibition scholarship, which enabled him to spend six months at the Cape of Good Hope Observatory in South Africa and visit major European and American observatories, learning the latest techniques in astrophysics.
Baldwin served as assistant astronomer at Melbourne Observatory for seven years from 1908-1915 until Pietro Baracchi retired in 1915. Baldwin then became Acting Government Astronomer until finally the government appointed him Government Astronomer in 1920. He held this position until the Observatory closed in 1944, and died the following year. Because Baracchi chose to live in St Kilda, Baldwin lived in the Astronomer's Residence from 1910 until 1944, with his wife, two sons and a daughter.
The administrative and daily scientific tasks of the Observatory severely limited the amount of research that Baldwin could undertake. Much of his efforts went into ensuring that the astrographic observations and magnetic data were published, leaving only a little time for his observations of variable stars with the 8 inch South Equatorial telescope. A capable scientist and administrator, he was less effective in fighting for resources for the Observatory from government bureaucrats and politicians.
Baldwin retired upon the closure of Melbourne Observatory in 1944.
Simon, Phillip (1979). 'Baldwin, Joseph Mason (1878-1945)', Australian Dictionary of Biography, Vol. 7, Melbourne University Press, pp.157-158.