Its nature and intention are explained by No.

10 of the 'explanatory observations' which he attached to it.

It is as follows; 'All the signals contained in the general printed Signal Book which are likely to be needful on the present occasion being provided for in this Signal Book, the signals as appointed in the general Signal Book will only be made either in conformity to the practice of some senior officer present, or when in company for the time being with other ships not of the fleet under the admiral's command, and unprovided with these particular signals.' It was therefore probably issued experimentally, but what the 'present occasion' was is not indicated.

It contains none of the additional signals of 1782-3.
[4] Knowles was of course too old in 1830 for his memory to be trusted as to details.

A note in his handwriting upon a copy of his code in possession of the present baronet gives its story simply as follows: 'These signals were written in 1778, as an idea--altered and published--then altered again in 1780--afterwards arranged differently in 1787, and finally in 1794; but not printed at Sir C.H.