In some of the unsolved mysteries that have occurred during the last few years the presence of a highly trained intellect at the first hour of the investigation might conceivably have led to the detection of the criminal. As a rule, it is only after the first examination is over and the case appears likely to be a difficult one, that the best brains of the department are brought to bear upon the facts, and it may then be too late for effective action. It should be made possible for a man who possesses a facility for this type of work to join the criminal investigation department without having to go through the routine work of a police constable, which will probably add nothing to his powers of following up a clue; but, on the other hand, this period of probation should be occupied by practical training in scientific methods of working. The present conditions both of payment and of status are not of the kind that will attract the highest type of brain to the work of criminal investigation, and yet there is no reason why it should not be made to offer the advantages of other branches of professional work. An apt illustration of the use of acute observation and deduction in solving a mystery is afforded by the strange story of a shooting accident, that, according to a writer in one of the leading morning papers, took place many years ago. A country gentleman was found lying dead upon a sofa, with the whole of the charge of a sporting gun in his body. The discharged gun was hanging in its usual place upon the wall, and there were no indications of any struggle having taken place. All the circumstances apparently pointed to the man having been murdered in his sleep, for it was impossible for him to have shot himself and have then replaced the gun upon the wall, and strong suspicion fell upon one of the servants in the house. This man was arrested, and would probably have been convicted had it not been for the detective noticing that the dead man's watch, which had been smashed by some of the shot, had been stopped early in the afternoon, and that at exactly the same moment the sun was focussed through a bottle of water that was standing upon the table in such a way that the ray fell upon the nipple of the gun upon the wall. Accordingly he loaded the gun again, hung it in the same spot, and placed a dummy figure upon the sofa, and as soon as the sun's rays passed through this unintended burning-glass and were focussed upon the gun, an explosion occurred and the contents were discharged into the figure. The writer has been unable to trace the date of this occurrence, but even if it is not founded upon fact it is not impossible, for there are undoubtedly cases where papers have been set on fire by the rays of the sun being concentrated upon them, through a bottle of water.