All the details of the writing and of the texture of the paper may be recorded by the camera, and a photographic enlargement may then be made to any required extent, so as to obtain what practically amounts to a record of the microscopical appearance. And the process has the additional advantage over microscopical examination that a large portion of the magnified surface may be examined at the same time, whereas in studying a document under the microscope, the view is restricted to a very minute portion of the surface. With the more general use of the typewriter it became possible to write libellous letters with much less risk of detection than in the case of letters written in ordinary pen and ink, for the machine eliminates the personal characteristics of the writer. The differences between various makes of typing ink are also less pronounced than the differences between different kinds of writing ink, and the proof of the identical character of two inks has, therefore, usually less significance. There are, however, certain typewriting inks, which are characteristic from the fact that they contain finely-divided carbon, and are, therefore, unlike most typing inks, exceedingly permanent, and it is also possible to distinguish between the more common violet aniline inks by the different degrees of resistance that they offer to bleaching reagents. Although it is not possible to identify the writer of a typed document by a study of the typing it is frequently not a difficult matter with the aid of the microscope to identify the machine upon which it was written. The principle underlying such identification is that the letters upon a new typewriter are arranged at very nearly equal spaces from each other and produce a fully horizontal line of writing. But after being in use for a very short period some of the letters are certain to get out of alignment, and to give faults in their relative position, which are usually reproduced every time those letters are struck. Thus, for instance, an "a" may be a little above the line and an "r" fall too much to the right, and these peculiarities will almost invariably recur throughout every scrap of writing done upon that machine, until the alignment has been adjusted. In no two machines are exactly the same variations in the relative positions of the different letters likely to occur. The chances of this happening is exceedingly remote, for there are some seventy letters and signs upon a typewriter. A practical illustration of the value of the evidence thus afforded, was seen in a case that occurred about a year ago. It was suspected that a letter had been written in collusion with a clerk in a certain office, and proof of this was thought likely to have considerable influence upon the issue of the trial.