"The third milestone," announced Peter pointing to a weatherbeaten slab just visible in the gloom.
"Yes, and the highest part of the road," added Entwistle. "It is about——".
He stopped abruptly. Away to the southward a vivid flash illuminated the sky, followed by three more in quick succession. Summer lightning would pale into insignificance compared with the intensity of those momentary sheets of lurid light.
"Good heavens—Barborough!" ejaculated the vet.
Barcroft made no remark. Failing his inability to read the face of his watch he placed the fingers of his right hand on his left wrist and carefully counted the pulse beats.
"Forty-five!" he announced calmly as the first of four loud detonations rent the air.
Crash—crash—crash—crash. It was as if he had been inside a tin bath and some one was belabouring it with a wooden mallet. Even allowing for the distance of the source of the sound the din was terrible.
A minute later came two more flashes, almost simultaneously, with forty-eight beats before the reports. Then one solitary flash followed by an even greater interval ere the detonation was heard.
"The brutes!" muttered Entwistle.
Again Peter made no audible comment. He was making a rapid mental calculation. Seventy pulsations to a minute: sound travels at roughly 365 yards to a second. Yes, that placed the scene of the raid at a distance of nine miles, and judging by the direction it was that populous town that had been the target for the missiles of the Zeppelin.