ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 861 



are perceptible to the eye, and we say that the hand trembles. ' But 

 as a matter of microscopic analysis the hand always trembles, and it is 

 an inalienable property of muscular contraction that it should.' The 

 regularity of this rhythm is destroyed by a voluntary effort at imita- 

 tion, and is somewhat interfered with, but not entirely broken, by 

 mental excitement. This rhythm differs in different handwritings, so 

 that it is well for the examiner, if practicable, to accustom himself to 

 the habitual rhythm of a genuine signature before expressing a 

 judgment on one which is questioned. 



The art of writing is a most complicated one, requiring the con- 

 sentaneous action of many muscles. When perfectly performed, it 

 should be nearly, if not quite, automatic, requiring very little mental 

 stimulus for its performance. If any act which should be automatic 

 demands our attention in order to execute it, the difficulty of perform- 

 ance increases. The ordinary mental stimulus suffers an emotional 

 diversion, which causes proportional muscular impotence. Hence 

 emotional disturbance causes a trembling handwriting. In cases of 

 writer's cramp, in which the muscles respond but sluggishly to the 

 will, and render the grasp of the pen faltering and uncertain, this 

 rhythm is greatly exaggerated or interrupted. Paralysis of the ulnar 

 nerve, rheumatism of the shoulder or wrist, neuralgia, and alcoholism, 

 may also interfere with the rhythm of progress. But in no case is the 

 failure of the rhythm so marked as in a voluntary attempt at imitation. 



(3) The rhythm of pressure. By this I mean, not the involuntary 

 and rapid action of the muscles, producing a microscopic wave as the 

 writing progresses, but a rhythmical alternation of light and dark 

 strokes, which is characteristic of some signatures, and which, in all 

 probability, is a variety of the rhythm of form ; yet, as it is revealed to 

 microscopic analysis rather than to ordinary vision, it may escape the 

 most expert imitator, and so become another factor in making up a 

 judgment in any case. 



If the microscopist carefully observes these three rhythms, being 

 careful of the illumination of the letters, he cannot fail to demonstrate 

 the difference between a genuine and an imitated signature. 



In a recent trial before Judge Crane, in Oakland, I was able to dis- 

 criminate between imitated and genuine signatures in a large number 

 of cases of remarkable similarity, prepared by a most talented writer, 

 as well as to testify to the genuineness of signatures in which there 

 was considerable variation of form. Mr. Geo. C. Hickox, also a 

 member of the Microscopical Society, and well known as an expert in 

 such matters, when his attention was called to this use of the compound 

 Microscope, declared to the Court that it was a new and wonderful 

 revelation, fixing beyond question the individuality of handwriting, 

 especially of signatures. 



Should this method of investigation be much used, as it ought to 

 be, it would be convenient to have a Microscope made for the purpose, 

 having a large stage with clips so as to hold paj)er of considerable 

 width, a tube of wide diameter to collect as much light as possible, a 

 very low power eye-piece, and a special objective of long focus and 

 large field of view." 



Ser. 2.— Vol. I. 3 L 



