(Roughly) Daily

Quod Erat Demonstrandum…

Barlow’s Wheel
St. Patrick’s College, Maynooth, Ireland
Today we remember Peter Barlow (1776-1862) for his mathematical tables, the Barlow Lens, and Barlow’s Wheel (1822). Electric current passes through the wheel from the axle to a mercury contact on the rim. The interaction of the current with the magnetic field of a U-magnet laid flat on the baseplate causes the wheel to rotate. Note that the presence of serrations on the wheel is unnecessary.

Thomas Greenslade, a professor emeritus at Kenyon, has a passion for the devices that have been used over the years to teach the principles of physics.  Happy for us, he is willing to share: there are hundreds of fascinating exhibits like the one above at “Instruments for Natural Philosophy.”

As we sit back under our apple trees, we might recall that it was on this date in 1790 that the first U.S. patent statute was signed into law by President Washington. Although a number of inventors had been clamoring for patents and copyrights (which were, of course, anticipated in Article I, Section 8, Clause 8 of the Constitution), the first session of the First Congress in 1789 acted on none of the petitions. On January 8, 1790, President Washington recommended in his State of the Union address that Congress give attention to the encouragement of new and useful inventions; and within the month, the House appointed a committee to draft a patent statute. Even then the process worked slowly: the first patent issued under this statute was signed by George Washington– on July 31, 1790, for Samuel Hopkins’ process to make potash and pearl ash.

It’s some measure of the power of IP to create value that, on this date in 1849, Walter Hunt of New York City was issued Patent No. 6,281– the first U.S. patent for a safety pin.  Strapped for cash, Hunt spent three hours on his invention, filed, then immediately sold the rights for the $400 that he needed.

The first U.S. patent, issued to Hopkins

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