human
A number of squares will appear in chequer-work upon the note, filled with hair lines in elliptic curves of various degrees of eccentricity, the squares to be alternately of red and black lines; the perfect mathematical coincidence of the extremity of the lines of different colours on the sides of the squares will be effected by machinery of singular fidelity. But even with the use of this machinery a person who has not the key to the proper disposition would make millions of experiments to no purpose. Other obstacles to imitation will also be presented in the structure of the note; but this is the one principally relied upon. It is plain that any failure in the imitation will be made manifest to the observation of the most careless, and the most skilful merchants who have seen the operation declare that the note cannot be imitated. The remarkable machine works with three cylinders, and the impression is made by small convex cylindrical plates.