We are not certain about the exact origins of headweighting as means for posture correction but there is evidence that late 1800s at etiquette schools Victorian young women in Europe where instructed to carry book on heads to improve posture.
One can well imagine carrying hard objects on head is an effective way to correct slouching but very impractical and debilitating. To prove the point, just place a book on your head and feel how slightest movement makes it fall.
The first documented record goes as far back as 1893 when John Corker filed a patent for a device called Gravity Helmet pictured below. Later, in 1912, another inventor by the name of A. Hamilton patented a device called Physical Developer. His objective was “…to develop the muscles of the neck, spine and lower limbs by placing the same upon the head and walking about”.
Later a device simply called Headweight aimed at physical training was patented in 1971 that incorporated lead shots to add weight. The weight of lead shots helps to strengthen neck muscles. But fastened headgears, in general, fail to offer the feature to align the spine. Alignment mechanism is perhaps the most important feature of any posture trainer. This fails to train the reflex system that very much governs the spinal alignment. With a stable headgear one can continue to slouch with no corrective consequence for posture.
Other devices with similar functions known as Neck Trainer, Fluid Filled Neck Exerciser, or Weight Bearing Headwear were patented later. These are very effective neck exerciser, but strong muscles alone do not necessarily translate into correct posture. Their failure to train the righting reflex makes those rather ineffective posture correctors.
On the other side of spectrum a patent for headgear called Advanced Posture Monitoring Device was filed in in 1994. It is essentially an electronic tilt sensor attached to a hat that sends an audio signal when the spine is out of alignment. The tilt sensor, on the other hand, fail to train the muscles that uphold the body in the new correct position. So, the effect is rather short term.
Posture Crown facilitates both the skeletal strengthening through its weight, as well as training righting reflex through its sliding function.