Your Atwater-Kent looks similar to my Stromberg-Carlson Neutrodyne from 1923. Clearly similar technology, although mine is near-mint, not a resto-job (sorry, I got lucky
). These are COOL old radios, well worth restoring, that still have a small but dedicated "cult-like" following.
These originally ran off batteries: that is, sets of wet cells that were big, heavy and a bit dangerous. Today transformers are the only way to go with them. Of course you can run these off of any transformers that give correct voltage, but If you want to spend the money, there is a specially-made transformer that is designed and made specifically to drive these old radios. It looks better, is fairly compact, is adjustable for a few different radios and has a few safety features built-in. I haven't got one yet, but I remember seeing them talked about online (and here!) when I first got my Neutrodyne, and plan to get one one day. You might want to look into that.
Congratulations on finding a rare early radio, and nice to know that another one will be saved and restored.
The very first commercial radio station broadcast was only made ca 1920, to give an indication of how early these are. Atwater-Kents were quite populat back then, and considered pretty good models. Tuning them is different - you have to experiment with each of the dials in sequence to dial in a station, and record the settings on the dials to find the station quickly the next time. Very different from modern tuning dials!
Oh, and try to find an early speaker to match it. One of those vertica; swan's-neck horns is best. More fun plus authentic sound that way! That said, if you use better-built but compatible headohones or speakers of more recent vintage (especially headphones), you'll find the sound quality on these is surprisingly good.
Here are some interesting related web links you might want to look at:
http://www.antiqueradios.com/forums/
http://reviews.ebay.com/1920s-Radios...00000001427481
http://en.wikipedia.org/wiki/Neutrodyne
http://www.radioblvd.com/20sRadio.html
http://www.digitaldeliftp.com/LookAr..._techspot.html