NA TURE 



6 9 



THURSDAY, JULY 20, 1911. 



A DETECTIVE'S VADE MECUM. 

 Science and the Criminal. By C. Ainsworth Mitchell. 

 Pp. xi"+24o. (London: Sir Isaac Pitman and 

 Sons, L,«d., 191 1.) Price 6s. net. 



IN the introduction to this fascinating- book is sug- 

 gested a special State department of criminal 

 investigation. Police routine work, walking beats, 

 directing traffic, quelling drunken street rows, is not, 

 the author thinks, an effective school of deductive 

 reasoning or scientific investigation. He would allow 

 his investigators to enter the State service by another 

 door ; he would train them in applied science, and 

 he would enable them to meet the clever criminal, as 

 Sherlock Holmes loved to do, on the same intellectual 

 plane. It would be unreasonable, however, to expect 

 even from investigators so trained the same unerring 

 instincts that surprise and delight us in the popular 

 detective of fiction. The detective story is, we must 

 remember, written backwards, and the author, having 

 carefully laid his clues along the track of the crime, 

 it is an easy matter for the detective, who is in the 

 secret, to pick them up as he goes along. 



Yet it is not impossible that the same faculty which 

 enables one to devise ingenious detective stories would 

 help in the actual detection of crime. Edgar Allan 

 Poe, the first and greatest of detective story- writers, 

 could not merely devise but detect. The wonderful 

 inductive reasoning in the story of the murder of 

 Marie Roger, in which, as in the popular puzzle game, 

 each clue, even to the most tiny, is fitted into its place 

 to complete the picture, was founded on the facts of 

 a real murder, which was perplexing the police at the 

 time, and the storyteller succeeded in unravelling the 

 mystery when the detectives had failed. In Sir A. 

 Conan Doyle the new department of criminal investi- 

 gation might find a distinguished first president ; than 

 Mr. Mitchell's volume there could be no better hand- 

 book for its schools. 



The book admirably indicates how, with ever-in- 

 creasing advantage and success, the weapons forged 

 by scientific research and discovery can be availed of 

 in society's interminable war against the criminal. 

 Of those agencies, electricity is one of the most effec- 

 tive, if not for detecting, for capturing the criminal. 

 The man in the street is not quick at grasping the 

 possibilities of a novel invention. At first it is popu- 

 larly regarded as a new toy, a matter of amazement 

 and amusement, but of no moment in the practical 

 affairs of men; so it was in our own day with the 

 telephone, the phonograph, and the biograph, with the 

 miracles of the X-rays, radium, and wireless tele- 

 graphy. A great invention must prove itself and so 

 live. Still, we find it hard to believe that the utility 

 of the telegraph was less in doubt, and that it was 

 as a criminal catcher it first established its reputation 

 with the public. 



" It is strange to reflect," writes Mr. Mitchell, " that 

 it was not until it had been employed in the capture 

 of a criminal that it was recognised in how many 

 NO. 2177, VOL. 87] 



directions the electric telegraph might be of service- 

 to mankind." 



Prior to that time the invention had been little 

 better than a failure, from a commercial point of view, 

 for though the railway companies had some time 

 before this realised the advantages of the new system 

 the Government had refused to have anything to say 

 to it. It was thus little short of a revelation to the 

 public when in 1845 the news was made known that a 

 suspected murderer had been arrested through the 

 agency of the telegraph. 



But the telegraph has learned a lot about detective 

 work since that time. It has even dabbled in photo- 

 graphy, and is now able not merely to describe but 

 to depict the fugitive criminal. The last word (so far 

 at any rate) on this subject appears to be the telecto- 

 graph invented by Mr. Thorne Baker, which, we 

 learn from Mr. Mitchell, "may also be used with 

 wireless installations for the transmission of simple 

 pictures or diagrams, and by whose means it would 

 be easy for a ship at sea to send or receive portraits." 

 A picture of King Edward VII., transmitted in this 

 fashion, and reproduced from the Daily Mirror, is one 

 of the most striking of the many illustrations of the 

 book. 



In every department of crime science seems to have 

 lent a hand to make easy the work of the detective 

 and to harass the criminal, who, with his own finger- 

 tips, is now compelled to print off an infallible means 

 of identification. The book is full of fairy tales of 

 science, more startling than the wonders of the 

 "Arabian Nights." The retort and microscope of the 

 analyst are the special bugbears of adepts in the 

 higher and more scientific walks of crime. 



In the old days the murderer caught red-handed 

 could safely deny the bloodstain was human, and the 

 microscope was unable to contradict him. It is not 

 so now. By a method recently discovered the analyst 

 examining the minutest stain of blood, dry, and 

 scarcely discernible to the naked eye on the garment 

 of a suspect, can tell to a certainty the species of 

 animal in the veins of which it originally flowed. 

 There is but one exception to the rule; the blood of 

 the anthropoid ape gives the same reaction as human 

 blood. One might fancy the spirit of Darwin rejoicing 

 in this singular confirmation of his theories. 



Mr. Mitchell possesses in a rare degree the gift of 

 interpreting between the man of science and the public. 

 The complicated process by which the blood of different 

 animals is differentiated in the test-tube is described 

 in clear and popular language easily understood even 

 by the least scientific. The ultimate result is summed 

 up in a few sentences, which make the matter plain 

 to the humblest intelligence. 



"A simple method of applying- the serum test 

 has recently been discovered. A small quantity 

 of human serum is placed into a series of 

 tubes, and into each of these is next intro- 

 duced one drop of the fresh blood of different animals 

 diluted with salt solution, or of the dried blood dis- 

 solved in that liquid. The tubes are now allowed to 

 stand from thirty to forty-five minutes, and then 

 examined. If, in the case of the blood of unknown 

 origin there is a faint red precipitate (of coagulated 

 blood), leaving the upper liquid clear, the blood is of 



