The horse began to move slowly along.
Jemmy was surprised and delighted to find how firm his footing was on the broad surface of the bags.

Growing more and more bold and confident as he became accustomed to his situation, he began presently to dance about, or rather to perform certain awkward antics, which he considered dancing, looking round continually, with a mingled expression of guilt, pleasure, and fear, in his countenance, in order to be sure that his father was not coming.

Finally, he undertook to make his horse trot a little.

The horse, however, by this time, began to grow somewhat impatient at the unusual sensations which he experienced--the weight of the rider being concentrated upon one single point, directly on his back, and resting very unsteadily and interruptedly there,--and the bridle-reins passing up almost perpendicularly into the air, instead of declining backwards, as they ought to do in any proper position of the horseman.

He began to trot forward faster and faster.