The problem
Toy water guns dribbled: each squeeze produced one weak stream because there was no stored energy.
The innovation
A hand-pumped pressurised reservoir that releases a continuous high-volume stream on the trigger.
How it worked
Air pressure stored in a chamber does the work, so the trigger only has to open a valve.
Why it mattered
One of the highest-grossing toys in history.
The legacy
Johnson used the royalties to fund research into thermo-electric energy conversion and battery technology.
You use this today
A summer staple in millions of households.
Sources
US Patent 4,591,071
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