AMERICAN DETECTIVE’S VIEWS/Mr. W. A. Pinkerton, chief of the Pinkerton Detective Agency in the United States, who is on a visit to London, in conversation with a representative yesterday, described the Hippodrome burglary as “ a burglar’s picnic.” There could be no doubt, said the detective, that nitro-glycerine was the explosive used to blowup the safe. “If the safe had a key-hole, asthe papers says,” he explained, “ it would be a simple matter to pour the stuff through and then use a fuse. In up-to-date American houses you wouldn't find safes like that. A safe with a key-hole is the easiest thing in the world to burgle if you g^ in for liquid explosives/'Experts who inspected the safe at the Hippodrome yesterday stated that the explosive used was nitro-glycerine.