These facts Nan, at least, did not learn till later; she ran off to the skating rink, secure in the thought that her father’s trouble with Mr. Ravell Bulson was over.  She hoped she might never see that grouchy fat man again.  But Fate had in store for her another meeting with the disagreeable Mr. Bulson, and this fell out in a most surprising way.

When Nan was almost in sight of the building where she expected to join her friends on skates, there sounded the sudden clangor of fire-truck whistles, and all other traffic halted to allow the department machines to pass.  A taxi-cab crowded close in to the curb where Nan had halted, just as the huge ladder-truck, driven by its powerful motor, swung around the corner.

Pedestrians, of course, had scattered to the sidewalks; but the wheels of the ladder-truck skidded on the icy street and the taxi was caught a glancing blow by the rear wheel of the heavier vehicle.

Many of the onlookers screamed warnings in chorus; but all to no avail.  Indeed, there was nothing the driver of the cab could have done to avert the catastrophe.  His engine was stopped and there was no possibility of escape with the car.

Crash! the truck-wheel clashed against the frail cab, and the latter vehicle was crushed as though made of paper.  The driver went out on his head.  Screams of fear issued from the interior of the cab as it went over in a heap of wreckage and the ladder-truck thundered on.

Nan saw a fat face with bulging eyes set in it appear at the window of the cab.  She was obliged to spring away to escape being caught in the wreck.  But she ran back instantly, for there were more than the owner of the fat face in the overturned taxi.

With the sputtering of the fat man there sounded, too, a shrill, childish scream of fear, and a wild yelp of pain—­the latter unmistakably from a canine throat.  Amid the wreckage Nan beheld a pair of blue-stockinged legs encased in iron supports; but the dog wriggled free.

“Hey!  Hey!” roared the fat man.  “Help us out of this.  Never mind that driver.  He ought to have seen that thing coming and got out of the way.  Hey!  Help us out, I say.”

Nobody seemed to be paying much attention to the fat and angry citizen; nor would Nan have heeded him had it not been for the appeal of those two blue-stockinged legs in the iron braces.

The fat man was all tangled up in the robes and in the broken fittings of the cab.  He could do nothing for himself, let alone assist in the rescue of the owner of the crippled little limbs.  The dog, darting about, barked wildly.

As Nan stooped to lift the broken cab door off the apparently injured boy, the dog—­he was only a puppy—­ran yapping at her in a fever of apprehension.  But his barking suddenly changed to yelps of joy as he leaped on Nan and licked her hands.

“Why, Buster!” gasped the girl, recognizing the little spaniel that she and Bess Harley had befriended in the snow-bound train.