Mr. Henry P. Babbage exhibited some detailed diagrams, to illustrate the Difference Engine of Messrs. Scheütz, of Stockholm, as an example of the ‘Mechanical Notation’ of Mr. Babbage, showing, that even the most complicated machinery might be described by a method at once so clear, concise, and easy of reference, as to render any written description unnecessary.

Diagram No. 1, exhibited the principal groups of the machine, and their relative connection.

Diagram No. 2, gave these groups more in detail, and a very complete outline of the machine, without entering into minute mechanical details.

Diagram No. 3, contained the full details of the whole machine, of which it was, in fact, a complete description. Each single Piece of the machine was indicated by a capital letter : every working Point was indicated by a small letter. The motion of every Piece might be traced back, through any number of Pieces, to the first mover; or forward, to show how it contributed to the final result. To give a full description of this diagram, would be to give a full description of the machine itself, and would occupy a volume of some bulk, as in this Difference Engine there were about four hundred separate Pieces, and about two thousand working Points. Any one acquainted with the Mechanical Notation, would be able to refer, at once, to any part of the machine, and to understand its action quickly. Those conversant with descriptions of machinery, written in ordinary language, could say how laborious it was to wade through them, even when aided by a good index, and would, therefore, be able to appreciate this facility of reference.