44 



Popular Science Monthly 



Testing two pieces of strap, one found at the scene 

 of the murder, the other in a suspect's pocket 



from an anaemic person. Often the field is 

 narrowed down to one or two persons. 



The chemists examined the scrapings 

 from the murdered man's finger-nails. 

 Under the microscope they found shreds of 

 human hair and fine particles of blue cloth. 

 The murdered man had worn a suit of dark 

 gray. There was no trace of blue dye in it. 

 Evidently, the cloth must have been torn 

 from the coat of the murderer. 



With the chemists' report before him, 

 Inspector Faurot narrowed the search 

 down to the mining engineer's two enemies. 

 And the chemical and microscopic clues 

 furnished by the Central Testing Labora- 

 tory enabled him at once to charge the 

 tubercular suspect with the crime. 



But what of the strap? How did that 

 figure in the case? Was it the same as the 

 piece found in the suspect's coat pocket? 

 To answer the question, comparative tests 

 were carried out in the Central Testing 

 Laboratory. Both pieces were stretched 

 until they broke. Thus their tensile 

 strength was determined. The readings of 

 the machine were identical for both pieces. 



When the suspect confessed, he said that 

 he had opened the bundle of papers hoping 

 to find an old mining report which he could 

 use to make a favorable report on his mine. 

 He had intended to forge the murdered 

 man's signature. 



A Pneumatic Device for Destroying 

 Devastating Animals 



IT has been estimated by the Govern- 

 ment that ten million dollars' worth of 

 crops are annually destroyed by ground 

 squirrels in the United States. Besides, 

 these animals are said to transmit such 

 diseases as the Bubonic plague. To make 

 war upon them, therefore, an unusually 

 handy and effective device has been in- 

 vented by Irving D. Charlton and Professor 

 W. T. Shaw, of the Department of Zoology, 

 State College of Washington. It consists 

 of a circular container which is filled with 

 some poisonous liquid such as carbon 

 bisulphide. A handle is geared to a suction 

 fan in the device. As it is turned the fan 

 causes a current of air to enter the opening 

 formed by the inner wall of the circular 

 container. The air current strikes against 

 a perforated disk which is mounted on the 

 fan-shaft and which rotates with it. The 

 air is then deflected and flows towards the 

 outer rim of the disk, some of it going 

 through the perforations into the liquid in 

 the container and some of it going through 

 the wetted perforations nearer the top of 

 the device. The air then proceeds along 

 towards the fan, carrying some vaporized 

 liquid with it. On reaching the fan the 

 mixture of vaporized liquid and air is 

 forced by the fan down the discharge pipe. 



The gas is forced through the pipe into the 

 burrow and the animals therein are asphyxiated 



