200 THE AMEKICAN MONTHLY [September, 



A variety of scales have been used for mapping out and measuring 

 the absorption bands, the best being that in the Zeiss instrument re- 

 ferred to, where the scale is ruled to read in wave lengths. In deter- 

 mining the exact location of the absorption bands it is essential that 

 the eye should be kept in a fixed position, as the least motion on the 

 part of the observer alters the apparent relation of the bands to the 

 bright lines of the scale, sufficient to confound, for example, a spectrum 

 of blood with that of some other red fluid. Prof. Moses C. White, of 

 Yale College, a member of this Society, who has had a long and varied 

 experience in the use of the microscope in medico-legal cases, a few 

 years since devised and perfected a micro-spectroscope which entirely 

 overcomes the requirement of holding the eye steadily, and renders the 

 practical'utility of this feature of the instrument equal to its theoretical 

 value. 



All the best forms of modern micro-spectroscopes are provided with 

 an arrangement whereby the spectrum of a known solution may be ex- 

 amined in direct comparison with the one under observation. The 

 great delicacy of this instrument, and the importance of its application 

 in legal examinations, can hardly be overestimated. Mr. Sorby and 

 others have claimed they were able to reveal the presence of a single 

 blood corpuscle by its spectrum, and their observations are confirmed 

 by Prof. Theodore G. Wormley, of the University of Pennsylvania. 

 The delicacy of the test may be better understood when we remember 

 that the estimated weight of a human-blood corpuscle is about one five- 

 hundrcd-millionth of a grain. 



By the aid of these instruments, and through discoveries already made, 

 the foundation has been laid for a branch of investigation in criminal 

 cases which will at no distant day be better understood. I i^efer to the 

 critical and systematic study of dyes and other substances used in the 

 manufacture of textile fabrics. It frequently happens that wool, cotton, 

 and other fibres are found on murderous weapons submitted to experts 

 for examination. These often contain artificial coloring matter, which 

 may or may not correspond to similar fibres in the clothing worn by 

 the victim or the accused. In an examination of a suspected blood 

 stain, involving the question of crime, the micro-spectroscope may be 

 used to corroborate other tests. While it enables us to discriminate be- 

 tween the coloring principles of blood and other fluids, it does not as- 

 sist in distinguishing between the blood of difterent animals. 



Considerable attention has been given of late to the microscopical ex- 

 amination of handwriting, both in criminal and civil cases. Differing 

 from the views of most writers on the subject, I consider the instrument 

 of no aid in forming an opinion as to the author of a given specimen 

 of penmanship, its value being confined to the determination of altera- 

 tions and changes made in the original. The slightest derangement 

 in the fibres on the finished surface of the paper cannot be restored by 

 the most skilful forgers. It is impossible to make an erasure of either 

 pencil, pen and ink, or printed lines, which the microscope will not 

 detect. 



One of the commonest methods employed in imitating handwriting 

 is to first take a pencil sketch or tracing, which is afterwards inked and 

 the pencil marks erased. No matter how delicately this erasure is per- 

 formed, under the proper lens the surface of the paper will disclose 



