“That is our Battery Test-Box,” explained the Inspector. “There are four thousand wires connected with it—two thousand going to the instruments up-stairs, and two thousand connected with the battery-jars. When I complete the circuit by connecting any couple of these buttons, the influence of the current is at once perceived.”
He took a piece of charcoal, as he spoke, and brought it into contact with two of the knobs. The result was to convert the coal instantly into an intense electric light of dazzling beauty. The point of an ordinary lead pencil applied in the same way became equally brilliant.
“That must be a powerful battery,” remarked the detective.
The Inspector smilingly took two handles from a neighbouring shelf and held them out to his visitor.
“Lay hold of these,” he said, “and you will feel its powers.”
The detective did as directed, and received a shock which caused him to fling down the handles with great promptitude and violence. He was too self-possessed a man, however, to seem put out.
“Strong!” he said, with a short laugh; “remarkably strong and effective.”
“Yes,” assented the Inspector, “it is pretty powerful, and it requires to be so, for it does heavy work and travels a considerable distance. The greater the distance, you know, the greater the power required to do the work and transmit the messages. This is the battery that fires two signal-guns every day at one o’clock—one at Newcastle, the other at South Shields, and supplies Greenwich time to all our principal stations over a radius of three hundred miles.—I sent the contents of one hundred and twenty jars through you just now!”
“That’s curious and interesting; I may even say it is suggestive,” returned the detective, in a meditative tone. “Double that number of jars, now, applied to the locks of street doors at night and the fastenings of windows would give a powerful surprise to burglars.”
“Ah, no doubt, and also to belated friends,” said the Inspector, “not to mention the effect on servant-maids in the morning when people forgot to disconnect the wires.”