In Vol. 9 of Dr. Albo (pg. 32) it states “the method by which this divination is accomplished was first alluded to in Hocus Pocus Junior in 1624″, though I was unable to find the reference. A detailed account of how it works can be found in Dr. Albo Vol. 5 (pg. 218). Ads started appearing c. 1926 in The Sphinx for Floyd Thayer’s elegant wooden version. The earliest ad that I could find for the more common brass and nickel plated pictured on this page was c. 1929.
These older versions are the best ones, all recent metal ones I have tried are nowhere near as well made or precise.
Effect: The audience may set the clock at any hour they desire and close the sliding lid. The performer may turn his back, or leave the room while this is being done, yet immediately upon his return he names the hour at which the clock is set, without even touching it.
This little specialty is beautifully made of metal, nickel plated, and is small enough to carry in the vest pocket nicely. Positively no extra devices are used.( Post Source: martinsmagic.com - click for details )