The 1961 edition of this book starts on page 5 so, I have made alterations to the total page count. It now reflects that the book has 149 numbered pages, instead of 153.

This brings me to the unnumbered pages... The index, which hasn't any page numbers, is 4 pages in length, with the final page of the index is printed on the "recto" side of the back end papers, and therefore not counted.

Other than these discrepancies, that I have noted for my own use, this is one of my favorite childhood books. It encouraged me to follow my path toward a life-long engineering career and also taught me to never stop asking questions and searching for the answers.