The 1948 work Dali Atomicus explores the idea of suspension, depicting three cats flying, water thrown from a bucket, an easel, a footstool and Salvador Dalí all seemingly suspended in mid-air. The title of the photograph is a reference to Dalí’s work Leda Atomica (at that which can be seen in the right of the photograph behind the two cats.)
Halsman reported that it took 28 attempts to be satisfied with the result. This is the unretouched version of the photograph that was published in LIFE magazine. In this version the wires suspending the easel and the painting, the hand of the assistant holding the chair and the prop holding up the footstool can still be seen.
The frame on the easel is still empty. The copyright for this photo was registered with the U.S. Copyright Office but according to the U.S. Library of Congress was not renewed, putting it in the public domain in the United States and countries which adopted the rule of the shorter term. [source]
For those interested, a high resolution 42.9 mb TIFF file of Dali Atomicus is available online at the Library of Congress