The Thaumatrope: Its Retribution -- August 25, 2014

Charles Babbage was one of the great polymaths of the 19th Century.  He is regarded as one of the fathers of computers because of his work on the Difference Engine and the Analytical Engine.  Here, in a passage from this memoir Passages From the Life of a Philosopher he talks about the thaumatrope.  Sir William Herschel was an astronomer.

The image is from The Young Folk's Cyclopædia of Games and Sports by John Denison Champlin and Arthur Elmore Bostwick, 1890. http://bigvriotsquad.blogspot.com/2014/02/zoetrope-27-february-2014.html

The Thaumatrope.
 

One day Herschel, sitting with me after dinner, amusing himself by spinning a pear upon the table, suddenly asked whether I could show him the two sides of a shilling at the same moment.

I took out of my pocket a shilling, and holding it up before the looking-glass, pointed out my method. "No," said my friend, "that won't do;" then spinning my shilling upon the table, he pointed out his method of seeing both sides at once. The next day I mentioned the anecdote to the late Dr. Fitton, who a few days after brought me a beautiful illustration of the principle. It consisted of a round disc of card suspended between the two pieces of sewing-silk. These threads being held between the finger and thumb of each hand, were then made to turn quickly, when the disc of card, of course, revolved also.
 

Upon one side of this disc of card was painted a bird; upon the other side, an empty bird-cage. On turning the thread rapidly, the bird appeared to have got inside the cage. We soon made numerous applications, as a rat on one side and a trap upon the other, &c. It was shown to Captain Kater, Dr. Wollaston, and many of our friends, and was, after the lapse of a short time, forgotten.

Some months after, during dinner at the Royal Society Club, Sir Joseph Banks being in the chair, I heard Mr. Barrow, then Secretary to the Admiralty, talking very loudly about a wonderful invention of Dr. Paris, the object of which I could not quite understand. It was called the thaumatrope, and was said to be sold at the Royal Institution, in Albermarle-street. Suspecting that it had some connection with our unnamed toy, I went the next morning and purchased, for seven shillings and sixpence, a thaumatrope, which I afterwards sent down to Slough to the late Lady Herschel. It was precisely the thing which her son and Dr. Fitton had contributed to invent, which amused all their friends for a time and had then been forgotten. There was however one additional thaumatrope made afterwards. It consisted of the usual disc of paper. On one side was represented a thaumatrope (the design upon it being a penny-piece) with the motto, "How to turn a penny."

On the other side was a gentleman in black, with his hands held out in the act of spinning a thaumatrope, the motto being, "A new trick from Paris."