The autograph consists of 5 pages. The kind of paper and the way of writing of the primary four pages are similar, page 5 differs. See Addition 1. The first four pages of the autograph are a Frühfassung, a concept with little notices and corrections. Bars 111 and 112 are crossed out.
The fifth page has a different character. On this page J.S. Bach wrote a little composition, the primary six bars, followed by the three themes in tonic position (not transposed). On the fifth page thirteen bars are written down.
On this page C.Ph. E. Bach notated a the remark ‘”Über dieser Fuge, wo der Nahme B.A.C.H. im Contrasubject angebracht worden, ist der Verfasser gestorben“.
C. Ph. E. Bach was involved in the publication of the first (revised) edition of The Art of Fugue in May of 1751. Contrapunctus 14 is incuded with title “Fuga a 3 Soggetti’. Remarkable fact is that only the first six bars of page 5 are enclosed, the last part with the 3 themes omits.
Musically the fugue consists of three parts, in each one a theme is introduced up to three themes. In the first revised version also the end of the first musical part is changed, bars 111 up to 114. In the autograph bar 111 and 112 are crossed out, see figure 1.
In comparison with the autograph, in the first revised version a bar is added with the subdominant to complete the cadence. Also the crossed out bars, bar 111 and 112, are included and changed. In bars 113 and 114 the tenor is changed. Figure 1 and 2 shows this part of the autograph, figure 3 and 4 the same part of the first edition.