Atom at that time was written by Gardner Fox--perhaps the single most important writer in DC at that time. With a career that ran back into the 1940s, Fox was a veteran comic hack who could turn out fun stories based on any number of different characters. It was Fox who formed the JLA, who help craft the updated versions of many DC icons such as Flash and Hawkman, who created the idea of the multi-verse to codify how the Golden Age characters related to their Silver Age counterpoints. He did a lot of important stuff.
Fox's weak point was probably characterization--the superheroes he wrote about never really develop truly distinctive personalities. But he more than made up for this with his mastery of plot and story.
Atom #9 (November 1963) starts out with a radiation leak in Ray Palmer's lab. He loses consciousness for a moment while a phantom version of himself ("a radioactive emanation of Ray Palmer's life-force" is the brief explanation) comes into existence. When Ray regains his senses, he learns that thieves have stolen some equipment being delivered to his lab. He pursues the thieves, at first unaware that another version of himself is in turn chasing him with murderous intent.
The second story featured the Time Pool--a device invented by a friend of Palmer's that can send a magnet back in time to retrieve artifacts. The Atom often hitches a ride on the magnet just to help out with this somewhat bizarre form of research. In this instance, Atom ends up in
Both stories are unpretentious fun. Told in a very economical fashion, they cover all the plot points one by one while still leaving room for some nifty action scenes.
And the fight scenes are what really make the story. The Atom was fortunate to have Gil Kane as his artist. Kane never drew an uninteresting panel in his life and his work here is infused with his typical energy. Whether Atom is pulling down on a thug's tie in order to bump his head against a second thug or playing a deadly game of hide-and-seek through desk drawers with his phantom double, it all comes across as tremendous fun.
Today, we often see story arcs that run through many issues--thus making them appropriate for being reprinted in trade paperbacks as a single epic tale. This is not a bad thing by itself--some stories should be epics. But it doesn't hurt to remember that there are stories that only need to be a few pages long to get the job done.