"Not very. Certainly not within a mile."
"But, uncle, can you calculate the distance of the lightning?" Harold asked.
"Unquestionably, or I should not have spoken with so much confidence. Robert imagined, as most people do, that a flash is near in proportion to its brightness; but that is no criterion. You must calculate its distance by the time which elapses between the flash and the report. Sound travels at the rate of about a mile in five seconds. Should any of you like to calculate the distance of the next flash, put your finger on your pulse, and count the number of beats before you hear the thunder."
An opportunity soon occurred. A vivid flash was followed after a few seconds by a roll, and then by a peal of thunder. All were busy counting their pulses. Mary ceased when she heard the first roll, exclaiming "Five!" The others held on until they heard the loud report, and said "Seven." Dr. Gordon reported only six beats of his own pulse, remarking,
"That flash discharged itself just one mile distant. Our pulses are quicker than seconds; and yours quicker than mine. Sound will travel a mile during six beats of a person of my age, and during seven of persons of yours."
"But, father," argued Mary, "I surely heard the thunder rolling when I said five."
"So did I," he answered; "and that proves that although the lightning discharged itself upon the earth at the distance of a mile, it commenced to flow from a point nearer overhead."
The young people were so deeply interested in these calculations, that they felt less keenly than they could have imagined possible the discomfort of the storm. This was Dr. Gordon's intention. But at last Mary and Frank winced so uneasily, when flashes of unusual brightness appeared, that their father remarked, "It is a weakness, my children, to be afraid of lightning that is seen and of thunder that is heard--they are spent and gone. Persons never see the flash that kills them--it does its work before they can see, hear, or feel."
At this instant came a flash so keen, that it seemed to blaze into their very eyes, and almost simultaneously came a report like the discharge of a cannon. Dr. Gordon's lecture was in vain; all except him and Harold started to their feet. Frank ran screaming to his father. Mary rushed to a pile of bedding, and covered herself with the bed-clothing. Robert looked at Mary's refuge, with a manifest desire to seek a place beside her. Harold fixed his eye upon his uncle, with a glance of keen inquiry.
"This is becoming serious," said the Doctor anxiously. "Something on the premises has been struck. Stay here, children, while I look after the servants. Your safest place is in the middle of the room, as far as possible from the chimney and walls, along which the lightning passes."