I’m rather pleased to be writing a paper on number counts of galaxies for the first trenche of Herschel papers as this allows me to reference William Herschel himself. The great astronomer, besides his various other discoveries, was the first to use counts of the number of stars as a function of their brightness and the direction of the observations, to determine the disk-like shape of our own galaxy. Similar techniques are used today to study the evolution of galaxies in the distant reaches of the universe.
I’m also pleased to see that Herschel’s papers, and, as far as I can tell, much of the journal in which they were published – Philosophical Transactions of the Royal Society – is available online via ADS. You can see Herschel’s counts paper here: