Blow book

The blow book, better known as a magic coloring book in modern variations, is a classic magic trick that has been performed for hundreds of years. It was most popular from the 16th to the 19th century, when variations of the concept were a staple of the book publishing trade. It has been referred to as the oldest example of a manufactured prop used for magic. It remains a common trick today, albeit mostly performed for children, preferably at birthday parties or other events due to the visual nature of the illusion.

The magician presents a book and riffles through it, showing a number of images in black and white. The book is then closed and a flourish is performed, normally involving audience participation, originally having an audience member blow on the outside of the book. The magician picks up the book and riffles it again, revealing that the images are now colored, or have changed completely into different images depending on the nature of the book.

The blow book is one of the oldest magic tricks. It has a history that is well-documented in historical sources, because the trick is based on a device that was only really practical after the widespread introduction of the printing press in 1450, which created a market for inexpensive paper and binding that the trick relies upon.

The earliest known mention of the concept was by Gerolamo Cardano in 1550, who described the trick by mentioning "conjurors show different and always unlike pictures in one and the same book". Another early mention is by Reginald Scot in his book The Discoverie of Witchcraft, published in 1584. This work examined witchcraft and revealed the tricks involved, ultimately concluding that witchcraft was not real. As part of this discussion he mentions the use of blow books, and goes on to describe how to prepare a book that the magician would then "whew you everie leafe to be painted with birds, then with beasts, then with serpents, then with angels, etc." He realized that the preparation might be beyond the capabilities of many would-be magicians, and directs his readers to "buie for a small value the like booke, at the shop of W. Brome in Powles churchyard", the earliest known example of a magic prop for sale. William Broome of St. Paul's in London was active between 1577 and 1591. A similar description of the blow book was published in French the same year by Jean Prévost.

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