The statement in the text
A. The ball as it leaves the pitcher's hand, rotating on its horizontal axis and traveling at an initial velocity of 150 feet a second or nearly two miles a minute.
First let's ask if the release speed is reasonable. The author claims 150 ft/sec, which corresponds to 102 mph, or 1.7 (or nearly 2, as the author says) miles/minute. That speed is certainly possible but is on the extreme upper end of the spectrum of today's MLB pitchers. Although we have no way of knowing for sure, it is doubtful that anyone could pitch that fast back in 1920.
The part about rotating on its horizontal axis is a reasonable statement as it approximates the spin axis for a typical four-seam fastball thrown with backspin or for a so-called "12-6" curveball thrown with topspin. It both cases, the spin axis is horizontal.
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